/* cyrillic-ext */
@font-face {
  font-family: 'Golos Text';
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
  src: url(/assets/fonts/font-d3534b8d279e.woff2) format('woff2');
  unicode-range: U+0460-052F, U+1C80-1C8A, U+20B4, U+2DE0-2DFF, U+A640-A69F, U+FE2E-FE2F;
}
/* cyrillic */
@font-face {
  font-family: 'Golos Text';
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
  src: url(/assets/fonts/font-d324f9941b3a.woff2) format('woff2');
  unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116;
}
/* latin-ext */
@font-face {
  font-family: 'Golos Text';
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
  src: url(/assets/fonts/font-44e514ae89e3.woff2) format('woff2');
  unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C0, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
/* latin */
@font-face {
  font-family: 'Golos Text';
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
  src: url(/assets/fonts/font-e0c165192dac.woff2) format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
/* cyrillic-ext */
@font-face {
  font-family: 'Manrope';
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
  src: url(/assets/fonts/font-842459da81f9.woff2) format('woff2');
  unicode-range: U+0460-052F, U+1C80-1C8A, U+20B4, U+2DE0-2DFF, U+A640-A69F, U+FE2E-FE2F;
}
/* cyrillic */
@font-face {
  font-family: 'Manrope';
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
  src: url(/assets/fonts/font-9b2d027172a3.woff2) format('woff2');
  unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116;
}
/* greek */
@font-face {
  font-family: 'Manrope';
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
  src: url(/assets/fonts/font-ed7393f42d27.woff2) format('woff2');
  unicode-range: U+0370-0377, U+037A-037F, U+0384-038A, U+038C, U+038E-03A1, U+03A3-03FF;
}
/* vietnamese */
@font-face {
  font-family: 'Manrope';
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
  src: url(/assets/fonts/font-1f3ea86e40d9.woff2) format('woff2');
  unicode-range: U+0102-0103, U+0110-0111, U+0128-0129, U+0168-0169, U+01A0-01A1, U+01AF-01B0, U+0300-0301, U+0303-0304, U+0308-0309, U+0323, U+0329, U+1EA0-1EF9, U+20AB;
}
/* latin-ext */
@font-face {
  font-family: 'Manrope';
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
  src: url(/assets/fonts/font-ee75508933e6.woff2) format('woff2');
  unicode-range: U+0100-02BA, U+02BD-02C5, U+02C7-02CC, U+02CE-02D7, U+02DD-02FF, U+0304, U+0308, U+0329, U+1D00-1DBF, U+1E00-1E9F, U+1EF2-1EFF, U+2020, U+20A0-20AB, U+20AD-20C0, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
/* latin */
@font-face {
  font-family: 'Manrope';
  font-style: normal;
  font-weight: 400 700;
  font-display: swap;
  src: url(/assets/fonts/font-4872f2a6dc9a.woff2) format('woff2');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}


/* Popov Academy — academic editorial identity. */
:root{--paper:#fff;--ink:#162535;--muted:#596571;--line:#dbe1e7;--blue:#1d448c;--blue-dark:#142f61;--navy:#162e50;--soft:#f2f5f8;--white:#fff;--sans:'Golos Text',Arial,sans-serif;--display:'Manrope','Golos Text',Arial,sans-serif;--serif:Georgia,'Times New Roman',serif}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:28px}body{margin:0;background:var(--paper);color:var(--ink);font:1rem/1.7 var(--sans);-webkit-font-smoothing:antialiased}a{color:inherit;text-decoration:none}button,input,select{font:inherit}button,a,summary{-webkit-tap-highlight-color:transparent}button,summary{cursor:pointer}img{display:block;max-width:100%;height:auto}h1,h2,h3,h4,p,figure{margin:0}h1,h2{font-family:var(--display);font-weight:500;letter-spacing:-.052em;line-height:1.16}h1{font-size:clamp(2.5rem,4.5vw,4.5rem)}h2{font-size:clamp(2rem,3.25vw,3rem)}h3{font-size:1.375rem;font-weight:500;letter-spacing:-.025em;line-height:1.35}p+p{margin-top:1em}a,button{transition:color .15s,background .15s,border-color .15s}a:focus-visible,button:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid #5f8bdb;outline-offset:5px}[hidden]{display:none!important}.wrap{width:min(1280px,calc(100% - 112px));margin-inline:auto;min-width:0}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.skip{position:fixed;top:-100px;left:20px;background:white;padding:12px 20px;z-index:100}.skip:focus{top:10px}

/* Navigation and global controls. */
.site-header{height:112px;background:#fff;border-bottom:1px solid var(--line);position:relative;z-index:20}.nav-wrap{display:flex;align-items:center;justify-content:space-between;height:100%;gap:35px}.brand{display:inline-flex;align-items:center;flex-shrink:0}.brand-name{font:700 1.45rem/1 var(--display);letter-spacing:.13em;display:block}.brand-name>span{display:block;font-size:.75rem;letter-spacing:.31em;margin-top:9px}.nav{display:flex;align-items:center;gap:30px;font-size:.875rem}.nav>a{padding:8px 0;white-space:nowrap}.nav>a[aria-current=page]{color:var(--blue);box-shadow:0 1px var(--blue)}.nav a:hover{color:var(--blue)}.nav .contact{border:1px solid var(--line);padding:12px 17px;margin-left:18px}.nav .contact:hover{border-color:var(--blue)}.menu-toggle{display:none;border:1px solid var(--line);background:white;padding:9px 13px;font-size:.875rem;color:var(--ink)}.button{display:inline-flex;justify-content:center;align-items:center;gap:28px;min-height:54px;padding:14px 24px;background:var(--blue);border:1px solid var(--blue);color:white;font-size:.875rem;font-weight:500;line-height:1.5}.button:hover{background:var(--blue-dark);border-color:var(--blue-dark)}.button.light{background:#fff;border-color:#fff;color:var(--navy)}.button.light:hover{background:#e7edf6}.button.outline{background:transparent;border-color:#9faab5;color:var(--ink)}.button.outline:hover{background:var(--soft);border-color:var(--ink)}.text-link{font-size:.875rem;border-bottom:1px solid currentColor;padding-bottom:4px;line-height:1.7}.text-link:hover{color:var(--blue)}.actions{display:flex;align-items:center;flex-wrap:wrap;gap:26px;margin-top:30px}.eyebrow{font-size:.75rem;letter-spacing:.13em;text-transform:uppercase;font-weight:500;color:var(--muted)}.tag{display:inline-block;font-size:.8125rem;line-height:1.5;color:var(--blue);background:var(--soft);padding:5px 9px}.tag.soon{color:var(--muted)}.section{padding:88px 0}.section-heading{display:flex;justify-content:space-between;align-items:flex-end;gap:40px;margin-bottom:38px}.section-heading .eyebrow{margin-bottom:19px}.section-heading p{max-width:370px;color:var(--muted);font-size:1rem}.section-heading>.text-link{flex-shrink:0}.grid-three{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:24px}.content-section{padding-bottom:80px}.page-head{padding:52px 0 48px}.breadcrumbs{font-size:.8125rem;line-height:1.7;color:var(--muted);margin-bottom:32px}.breadcrumbs a{border-bottom:1px solid #c5ced8}.page-head h1{max-width:1040px;margin-top:20px}.page-head h1 em{font-style:normal;color:var(--blue)}.page-head .lead{font-size:1.125rem;line-height:1.75;color:var(--muted);max-width:740px;margin-top:24px}.compact-head{padding-bottom:34px}.compact-head h1{font-size:clamp(2.4rem,4.5vw,4rem)}.page-grid{display:grid;grid-template-columns:minmax(0,760px) minmax(0,280px);gap:80px}.aside-note{border-top:2px solid var(--blue);padding-top:23px}.aside-note h3{font-size:1.1875rem}.aside-note p{color:var(--muted);font-size:1rem;margin-top:16px}.aside-note .button{margin-top:24px;width:100%;gap:12px}.service-note{font-size:.875rem;color:var(--muted);margin-top:18px}

/* Home: a real teacher, a clear statement, and evidence. */
.academy-hero{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:70px;padding:72px 0 66px;align-items:center}.hero-kicker{font-size:.8125rem;letter-spacing:.12em;display:flex;gap:18px;align-items:center}.hero-kicker span{color:var(--muted);font-size:.75rem;letter-spacing:.04em;padding-left:18px;border-left:1px solid var(--line)}.academy-hero h1{font-size:clamp(3.15rem,5.8vw,5.6rem);line-height:1.13;margin:29px 0 25px;letter-spacing:-.065em}.academy-hero h1>span{color:var(--blue)}.hero-copy{max-width:565px;font-size:1.125rem;color:var(--muted);line-height:1.75}.hero-subjects{margin-top:43px;display:flex;flex-wrap:wrap;gap:22px;font-size:.8125rem;color:var(--muted)}.hero-subjects span+span{border-left:1px solid var(--line);padding-left:22px}.hero-author{background:var(--navy);color:white}.portrait-mat{padding:28px 30px 0}.portrait-mat img{width:240px;height:285px;object-fit:cover;object-position:50% 32%;filter:grayscale(1)}.hero-author figcaption{padding:25px 30px 27px;font-size:.8125rem;color:#c1cede}.author-name{font:500 1.4375rem/1.3 var(--display);display:block;color:white;margin-bottom:5px}.hero-author figcaption>a{display:flex;justify-content:space-between;border-top:1px solid #4b5f7a;margin-top:22px;padding-top:15px;color:white;font-size:.875rem}.credentials{display:grid;grid-template-columns:1fr 1.25fr 1fr;padding:29px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line);gap:45px}.credential{border-right:1px solid var(--line);padding-right:25px}.credential:last-child{border:0}.credential strong{font:500 1.625rem/1.3 var(--display);letter-spacing:-.04em;display:block;margin-bottom:7px}.credential small{font:.875rem var(--sans);color:var(--muted)}.credential span{font-size:.8125rem;color:var(--muted);line-height:1.6;display:block}.home-teaching{display:grid;grid-template-columns:minmax(0,.9fr) minmax(0,1.35fr);gap:90px}.home-section-intro h2{margin:22px 0 25px}.home-section-intro>p{max-width:380px;color:var(--muted);margin-bottom:30px}.teaching-row{display:grid;grid-template-columns:30px minmax(0,1fr) 22px;gap:23px;padding:28px 0;border-top:1px solid var(--line)}.teaching-row:first-child{border-top:2px solid var(--ink);padding-top:25px}.teaching-number{font-size:.8125rem;color:var(--muted);padding-top:5px}.teaching-row h3{font:500 1.5625rem/1.35 var(--display);letter-spacing:-.045em}.teaching-row p{margin-top:10px;color:var(--muted);font-size:1rem;max-width:500px}.teaching-audience{display:block;margin-top:15px;font-size:.75rem;color:var(--muted)}.row-arrow{font-size:1.25rem;color:var(--blue)}.teaching-row:hover h3{color:var(--blue)}.teaching-note{border-top:1px solid var(--line);padding-top:22px;font-size:.875rem;color:var(--muted)}
.library-feature{background:var(--navy);color:#fff;padding:74px 0 30px}.library-feature .eyebrow{color:#b2c2d7}.library-feature h2{font-weight:400}.library-feature .section-heading{margin-bottom:40px}.library-editorial{display:grid;grid-template-columns:minmax(0,1.2fr) minmax(0,1fr);gap:65px}.featured-problem{padding:27px 0;border-top:1px solid #536881;border-bottom:1px solid #536881}.problem-caption{display:flex;justify-content:space-between;gap:15px;color:#b6c7dc;font-size:.8125rem}.problem-composition{display:grid;grid-template-columns:175px minmax(0,1fr);align-items:center;gap:40px;padding:36px 0 20px}.board{display:grid;grid-template-columns:repeat(8,1fr);width:100%;aspect-ratio:1;border:1px solid #8297b0}.board span{aspect-ratio:1;background:#e5edf7}.board .dark{background:#476184}.board .cut{background:var(--navy);border:1px dashed #94a9c4}.problem-composition h3{font:400 1.9rem/1.17 var(--display);letter-spacing:-.035em}.problem-composition p{font-size:.875rem;line-height:1.6;color:#b6c7dc;margin:17px 0 22px}.library-feature .text-link:hover{color:#b6c7dc}.reading-row{display:flex;justify-content:space-between;gap:20px;padding:22px 0;border-top:1px solid #536881}.reading-row:first-child{padding-top:22px}.reading-row>div>span{font-size:.75rem;color:#b6c7dc}.reading-row h3{font-size:1.1875rem;line-height:1.4;margin-top:8px;font-weight:400}.reading-row>span{align-self:center;font-size:1.25rem}.reading-row:hover h3{color:#c7dbfa}.reading-list>p{font-size:.8125rem;color:#b6c7dc;line-height:1.65;padding-top:12px}.library-paths{display:flex;align-items:center;gap:34px;flex-wrap:wrap;border-top:1px solid #536881;margin-top:44px;padding:25px 0 0;font-size:.8125rem}.library-paths>span{color:#b6c7dc;margin-right:auto}.library-paths a:hover{text-decoration:underline;text-underline-offset:4px}
.personal-approach{display:grid;grid-template-columns:1fr 1.05fr;gap:90px;border-top:1px solid var(--line)}.personal-approach h2{margin-top:22px;font-size:clamp(1.9rem,2.9vw,2.65rem)}.approach-copy{color:var(--muted)}.approach-copy .actions{color:var(--blue)}.home-journal{display:grid;grid-template-columns:1fr 1.05fr;gap:90px;padding:50px;background:var(--soft);align-items:center}.home-journal h2{margin-top:18px}.home-journal p{color:var(--muted)}.home-contact{padding:65px 0 75px;display:flex;align-items:center;justify-content:space-between;gap:40px}.home-contact p{color:var(--muted);margin-bottom:16px}.home-contact h2{font-size:clamp(2.2rem,4vw,3.5rem)}

/* Service pages and readable long-form content. */
.direction-card{border-top:1px solid var(--line);padding:27px 0 30px;display:flex;flex-direction:column;align-items:flex-start}.direction-card:hover{border-color:var(--blue)}.card-symbol{font:italic 1.75rem var(--serif);color:var(--blue);margin-bottom:22px}.direction-card h3{font:500 1.5rem/1.3 var(--display);letter-spacing:-.04em;margin-top:18px}.direction-card p{color:var(--muted);font-size:1rem;margin:16px 0 25px}.card-foot{display:flex;width:100%;align-items:center;justify-content:space-between;margin-top:auto;gap:15px;font-size:.8125rem;color:var(--muted)}.card-foot b{font-size:1.25rem;color:var(--blue);font-weight:400}.prose{max-width:760px;font-size:1.0625rem;line-height:1.85}.prose h2{font-size:2rem;margin:42px 0 20px;line-height:1.3}.prose h3{font-size:1.375rem;margin:28px 0 14px}.prose p{margin-bottom:20px}.prose ul,.prose ol{padding-left:24px}.prose li{margin:12px 0}.prose a{color:var(--blue);text-decoration:underline;text-underline-offset:4px}.prose .button{color:white;text-decoration:none}.prose>h2:first-child,.prose>section:first-child>h2{margin-top:0}.callout{background:var(--soft);border-left:2px solid var(--blue);padding:25px 30px;margin:28px 0}.callout p:last-child{margin-bottom:0}.formula{font:1.75rem/1.7 var(--serif);background:var(--soft);text-align:center;padding:24px;margin:25px 0;overflow-wrap:anywhere}.related{border-top:1px solid var(--line);margin-top:40px;padding-top:18px}.related h3{margin-top:12px}.bio-portrait{max-width:280px}.portrait{width:240px;max-width:100%;filter:grayscale(1);object-fit:cover}.timeline{margin:30px 0}.timeline-row{display:grid;grid-template-columns:120px 1fr;gap:30px;padding:22px 0;border-top:1px solid var(--line)}.timeline-row strong{font-weight:500}.timeline-row span{color:var(--muted);font-size:1rem}.project-row{display:grid;grid-template-columns:55px minmax(0,1fr) 195px;gap:32px;padding:32px 0;border-top:1px solid var(--line)}.project-index{font:400 1.25rem/1.5 var(--display);color:var(--muted)}.project-row h3{font-size:1.625rem;margin:14px 0}.project-row p{max-width:630px;color:var(--muted)}.project-action{text-align:right;padding-top:10px}.journal-banner{padding:45px;background:var(--soft);display:flex;align-items:center;justify-content:space-between;gap:40px}.journal-banner h2{font-size:2.5rem}.journal-banner p{max-width:600px;color:var(--muted);margin-top:20px}.journal-banner .button{flex-shrink:0}.contact-panel{display:grid;grid-template-columns:1fr 1fr;gap:0;margin-top:8px;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}.contact-option{padding:38px 40px 38px 0}.contact-option+.contact-option{padding-left:40px;padding-right:0;border-left:1px solid var(--line)}.contact-option p{margin:20px 0 28px;color:var(--muted)}

/* Library — utility comes before decoration. */
.library-tabs{display:flex;gap:32px;flex-wrap:wrap;border-bottom:1px solid var(--line);margin-top:32px}.library-tabs a{font-size:.9375rem;padding:0 0 15px}.library-tabs a[aria-current]{color:var(--blue);border-bottom:2px solid var(--blue)}.library-tabs span{font-size:.75rem;padding:3px 7px;margin-left:6px;background:var(--soft)}.library-shell{display:grid;grid-template-columns:240px minmax(0,1fr);gap:65px;align-items:start}.library-filter{background:var(--soft);padding:26px}.library-filter h2{font:500 1.0625rem/1.4 var(--sans);letter-spacing:-.02em;margin-bottom:18px}.library-filter label{display:block;margin:18px 0 7px;font-size:.875rem;font-weight:500}.library-filter input,.library-filter select{background:white;border:1px solid #b5c0cd;color:var(--ink);min-height:46px;width:100%;max-width:100%;padding:10px;font-size:.875rem;border-radius:0}.library-filter input::placeholder{color:var(--muted)}.filter-options{margin-top:16px}.filter-options summary{font-size:.875rem;color:var(--blue);padding:5px 0;line-height:1.5}.filter-reset{background:none;border:0;border-bottom:1px solid currentColor;font-size:.875rem;color:var(--muted);padding:0 0 3px;margin-top:22px}.filter-note{padding-top:24px;border-top:1px solid var(--line);margin-top:28px;font-size:.875rem}.filter-note p{color:var(--muted);margin-top:15px}.filter-note a{display:inline-block;color:var(--blue);margin-top:14px}.filter-note .tag{padding:0;background:none;color:var(--ink)}.catalog-top{display:flex;align-items:center;justify-content:space-between;gap:20px;padding-bottom:17px;font-size:.875rem}.catalog-top>span{font-size:.75rem;color:var(--muted)}.catalog-item{display:grid;grid-template-columns:35px minmax(0,1fr);gap:22px;padding:28px 0;border-top:1px solid var(--line)}.catalog-item:last-child{border-bottom:1px solid var(--line)}.catalog-index{font:400 1rem/1.6 var(--display);color:var(--muted)}.catalog-meta{display:flex;gap:16px;flex-wrap:wrap;font-size:.8125rem;color:var(--muted);margin-bottom:10px}.catalog-meta span:first-child{color:var(--blue)}.catalog-item h2{font:500 1.4375rem/1.35 var(--display);letter-spacing:-.035em}.catalog-item h2 a:hover{color:var(--blue)}.catalog-item p{font-size:1rem;color:var(--muted);margin-top:10px;max-width:650px}.catalog-bottom{display:flex;justify-content:space-between;gap:20px;margin-top:20px;font-size:.8125rem;color:var(--muted)}.catalog-bottom a{font-size:.875rem;color:var(--blue)}.empty-results{padding:32px;background:var(--soft)}.empty-results h2{font-size:1.75rem}.empty-results p{margin:18px 0 25px}.learning-section{border-top:1px solid var(--line);padding:60px 0}.path-grid{display:grid;grid-template-columns:1fr 1fr;gap:42px}.path-card{display:flex;flex-direction:column;align-items:flex-start;border-top:2px solid var(--blue);padding:26px 0}.path-meta{display:flex;justify-content:space-between;width:100%;gap:20px;color:var(--muted);font-size:.8125rem}.path-card h3{font:500 2rem/1.25 var(--display);letter-spacing:-.04em;margin:26px 0 16px}.path-card p{color:var(--muted);margin-bottom:24px}.path-card .text-link{margin-top:auto;color:var(--blue)}.path-card:hover h3{color:var(--blue)}.resource-banner{display:flex;align-items:center;justify-content:space-between;gap:50px;background:var(--soft);padding:40px;margin:0 0 70px}.resource-banner h2{font-size:2.25rem;margin:18px 0}.resource-banner p{max-width:650px;color:var(--muted)}.resource-banner .button{flex-shrink:0}.practice-principles{padding:32px;background:var(--soft);margin-bottom:65px}.practice-principles h2{font-size:2rem;margin-bottom:20px}.practice-principles h3{margin:30px 0 15px}.practice-principles p{max-width:800px;margin:15px 0}.practice-principles li{margin:15px 0}.practice-principles ol{padding-left:22px}.practice-principles .text-link{color:var(--blue)}.path-detail{display:grid;grid-template-columns:minmax(0,1fr) 280px;gap:70px}.path-step{display:grid;grid-template-columns:40px minmax(0,1fr);gap:28px;border-top:1px solid var(--line);padding:29px 0}.path-step h2{font-size:1.625rem;margin:14px 0}.path-step p{color:var(--muted);margin-bottom:18px}.path-steps{margin-bottom:35px}.step-number{font:400 1.25rem/1.5 var(--display);color:var(--blue)}.path-aside ul{padding-left:20px;color:var(--muted)}.path-aside li{margin:14px 0}.path-aside .aside-note+.aside-note{margin-top:38px}.method-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:35px}.method-grid>div{border-top:1px solid var(--line);padding-top:22px}.method-grid h3{margin:18px 0}.method-grid p{color:var(--muted)}.method-section{padding-top:50px}.resource-list{display:grid;grid-template-columns:1fr 1fr;gap:30px 50px}.resource-item{display:grid;grid-template-columns:25px minmax(0,1fr);gap:20px;border-top:1px solid var(--line);padding:28px 0}.resource-item h2{font-size:1.75rem;margin:17px 0}.resource-item p{color:var(--muted)}.resource-tip{border-top:1px solid var(--line);padding-top:17px;margin-top:17px}.resource-item .text-link{display:inline-block;margin-top:23px;color:var(--blue)}.resource-disclosure{max-width:800px;margin-bottom:70px!important}.resource-disclosure a{text-decoration:underline;text-underline-offset:4px}

/* Reading and practice surfaces. */
.article-header{max-width:1000px}.article-header h1{font-size:clamp(2.25rem,4.2vw,3.75rem);max-width:900px}.topline{display:flex;justify-content:space-between;gap:20px;align-items:center}.read-time{font-size:.8125rem;color:var(--muted)}.article-tools{display:flex;justify-content:space-between;align-items:center;gap:25px;margin-top:28px;font-size:.8125rem;color:var(--muted)}.print-button{background:white;border:1px solid var(--line);padding:10px 15px;font-size:.875rem;color:var(--ink);flex-shrink:0}.print-button:hover{border-color:var(--blue)}.article-layout{display:grid;grid-template-columns:minmax(0,760px) minmax(0,265px);gap:85px}.prerequisite{border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:20px 0;font-size:1rem}.prerequisite strong{font-size:.75rem;text-transform:uppercase;letter-spacing:.09em;font-weight:500}.prerequisite p{margin:7px 0 0;color:var(--muted)}.section-numeral{font:.875rem var(--sans);color:var(--blue);margin-right:10px}.attempt-note{color:var(--muted);font-size:1rem}.solution{border:1px solid var(--line);margin:16px 0;background:white}.solution summary{padding:20px 22px;font-weight:500;font-size:1rem;line-height:1.6}.solution summary:hover{color:var(--blue);background:var(--soft)}.solution[open] summary{border-bottom:1px solid var(--line)}.solution-body{padding:22px}.solution-body p:last-child{margin:0}.mistake-note{background:var(--soft);padding:24px}.mistake-note h3{font-size:1.125rem;margin:0 0 12px}.mistake-note p{margin:0;font-size:1rem}.article-side{font-size:.875rem}.article-side a{display:block;margin:15px 0;color:var(--muted)}.article-side a:hover{color:var(--blue)}.article-side .button{color:white}.article-side>.aside-note+.aside-note{margin-top:38px}.source-note{font-size:.8125rem;color:var(--muted);border-top:1px solid var(--line);padding-top:20px;margin-top:32px}.mini-board{width:225px;padding:20px;background:var(--navy);margin:28px auto}.answer-check{padding:24px;border:1px solid var(--line);margin:25px 0}.answer-check label{display:block;font-size:1rem;font-weight:500;margin-bottom:12px}.answer-check>div{display:flex;gap:12px}.answer-check input{width:140px;min-width:0;min-height:48px;padding:10px;border:1px solid #a5b2c1;font-size:1.125rem}.answer-check small{display:block;color:var(--muted);font-size:.8125rem;margin-top:10px}.answer-check .answer-feedback{font-size:1rem;margin:16px 0 0;line-height:1.6}.answer-check .answer-feedback:empty{display:none}.answer-feedback[data-result=correct]{color:#22633d}.answer-feedback[data-result=incorrect]{color:#963d25}

/* Portfolio: distinguish outcomes, testimonials, and original documents. */
.portfolio-nav{display:flex;gap:30px;flex-wrap:wrap;margin-top:32px;font-size:.9375rem}.portfolio-nav a{border-bottom:1px solid var(--line);padding:7px 0}.portfolio-nav a:hover{color:var(--blue);border-color:var(--blue)}.portfolio-facts{display:grid;grid-template-columns:1fr 1.3fr 1fr;gap:38px;padding:30px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}.portfolio-facts strong{font:500 2rem/1.3 var(--display);letter-spacing:-.04em;display:block;margin-bottom:12px}.portfolio-facts strong small{font:1rem var(--sans);color:var(--muted)}.portfolio-facts span{display:block;font-size:.8125rem;color:var(--muted)}.portfolio-facts a{color:var(--blue);border-bottom:1px solid #bdcadc}.outcome-grid,.cohort-grid,.profi-grid,.document-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:32px}.outcome-card{border-top:2px solid var(--blue);padding:25px 0 0;display:flex;flex-direction:column;align-items:flex-start}.outcome-number{font:400 3.45rem/1.15 var(--display);color:var(--blue);letter-spacing:-.06em;margin:26px 0 23px}.outcome-number small{font:1.125rem var(--sans);letter-spacing:0}.outcome-word{font-size:2.35rem;line-height:1.69}.outcome-card h3{font-size:1.3125rem;margin-bottom:16px}.outcome-card p{color:var(--muted);font-size:1rem}.outcome-card .evidence-note{margin-top:auto;padding-top:22px;font-size:.75rem}.evidence-note{font-size:.8125rem;color:var(--muted);margin-top:20px}.evidence-note a{border-bottom:1px solid var(--line)}.cohort-heading{margin:55px 0 27px}.cohort-heading h3{font-size:1.5rem}.cohort-heading p{color:var(--muted);margin-top:10px}.cohort-card{border-top:1px solid var(--ink);padding-top:21px}.cohort-card h4{font-size:1.25rem;font-weight:500;margin-bottom:8px}.cohort-card>p{font-size:.8125rem;color:var(--muted)}.cohort-card table{border-collapse:collapse;width:100%;margin-top:20px;font-size:1rem}.cohort-card th{text-align:left;color:var(--muted);font-size:.8125rem;font-weight:400;padding-bottom:10px}.cohort-card td{padding:9px 0;border-top:1px solid var(--line)}.cohort-card td:last-child,.cohort-card th:last-child{text-align:right}.cohort-card td:last-child{font-variant-numeric:tabular-nums;font-weight:500}.high-score{color:var(--blue)}.reviews-section,.education-section{border-top:1px solid var(--line)}.review-card{padding:30px 0;border-top:1px solid var(--line);display:flex;flex-direction:column;align-items:flex-start}.review-source{display:flex;justify-content:space-between;flex-wrap:wrap;gap:15px;width:100%;color:var(--muted);font-size:.75rem;margin-bottom:22px}.review-card blockquote{font:400 1.5rem/1.5 var(--serif);margin:0 0 28px;letter-spacing:-.012em}.review-card figcaption{margin-top:auto}.review-card figcaption strong{display:block;font-size:.9375rem;font-weight:500}.review-card figcaption span{display:block;font-size:.8125rem;color:var(--muted);margin-top:6px}.private-reviews{display:grid;grid-template-columns:1fr 1fr;gap:16px 45px}.private-reviews .review-featured{grid-column:1/-1;background:var(--navy);color:#fff;padding:42px;margin-bottom:12px;display:grid;grid-template-columns:minmax(0,2fr) minmax(0,1fr);gap:0 65px;border:0}.review-featured .review-source{grid-column:1/-1;color:#b9c9dc}.private-reviews .review-featured blockquote{font-size:1.875rem;margin-bottom:0}.private-reviews .review-featured figcaption{align-self:end}.review-featured figcaption span{color:#b9c9dc}.profi-heading{display:flex;align-items:center;justify-content:space-between;gap:30px;margin:35px 0 22px}.profi-heading h3{font-size:1.5rem}.profi-heading p{font-size:1rem;color:var(--muted);margin-top:12px}.profi-heading>a{font-size:.875rem;color:var(--blue);flex-shrink:0}.public-review h4{font-size:1rem;font-weight:500;margin:0 0 22px}.public-review blockquote{font-size:1.375rem;margin-bottom:18px}.public-review>p{font-size:1rem;color:var(--muted);margin-bottom:26px}.review-author{display:flex;flex-direction:column;gap:6px;margin-top:auto;font-size:.875rem}.review-author strong{font-weight:500}.review-author a{color:var(--blue)}.education-section{display:grid;grid-template-columns:1fr 1fr;gap:90px}.education-section h2{margin:22px 0 25px}.education-section>div>p{max-width:440px;color:var(--muted);margin-bottom:26px}.education-list article{border-top:1px solid var(--line);padding:25px 0}.education-list article:first-child{border-top:2px solid var(--ink)}.education-list article>span{font-size:.8125rem;color:var(--muted)}.education-list h3{font-size:1.375rem;margin:10px 0 12px}.education-list p{color:var(--muted)}.document-card{border:1px solid var(--line);display:flex;flex-direction:column}.document-card:hover{border-color:var(--blue)}.document-image{height:250px;position:relative;background:var(--soft);display:flex;align-items:center;justify-content:center;padding:23px;overflow:hidden}.document-image img{width:100%;height:100%;object-fit:contain;filter:none}.document-image.rotated-document img{position:absolute;width:165px;height:220px;max-width:none;transform:rotate(-90deg);padding:0}.document-caption{padding:25px;display:flex;flex-direction:column;flex:1}.document-caption>span{font-size:.75rem;color:var(--muted)}.document-caption h3{font-size:1.1875rem;line-height:1.35;margin:11px 0}.document-caption p{color:var(--muted);font-size:1rem;margin-bottom:20px}.document-caption b{display:flex;justify-content:space-between;gap:20px;font-size:.875rem;font-weight:500;margin-top:auto;color:var(--blue)}.document-full{padding:30px;background:var(--soft);max-width:1000px;margin:auto}.document-full .document-image{height:auto;background:transparent;padding:0;overflow:visible}.document-full img{width:auto;height:auto;max-height:1100px;object-fit:contain}.document-full .rotated-document{aspect-ratio:4/3}.document-full .rotated-document img{position:absolute;top:50%;left:50%;width:75%;height:auto;max-height:none;transform:translate(-50%,-50%) rotate(-90deg)}.portfolio-cta{margin:0 0 80px;padding:40px;background:var(--soft);display:flex;align-items:center;justify-content:space-between;gap:40px}.portfolio-cta h2{font-size:2.5rem;margin:18px 0}.portfolio-cta p{max-width:580px;color:var(--muted)}.portfolio-cta .button{flex-shrink:0}.portfolio-teaser{padding-bottom:84px}.testimonial-feature{display:grid;grid-template-columns:minmax(0,1.7fr) minmax(0,1fr);background:var(--soft)}.testimonial-feature .review-card{border:0;padding:40px}.testimonial-feature .review-card blockquote{font-size:1.625rem;line-height:1.6}.testimonial-feature .review-source{color:var(--muted)}.testimonial-feature .review-card figcaption span{color:var(--muted)}.teaser-evidence{padding:38px;background:var(--navy);color:#fff;display:flex;flex-direction:column;align-items:flex-start;justify-content:center}.teaser-evidence .tag{background:none;padding:0;color:#b9c9dc}.teaser-evidence strong{font:400 2.75rem/1.3 var(--display);letter-spacing:-.05em;color:#fff;margin:23px 0 20px;white-space:nowrap}.teaser-evidence p{font-size:1rem;color:#b9c9dc;margin-bottom:30px}.teaser-evidence .text-link:hover{color:#c9dcfa}

/* Footer. */
.site-footer{background:var(--ink);color:white;padding:45px 0 27px}.footer-top{display:flex;justify-content:space-between;align-items:center;gap:35px}.footer-links{display:flex;gap:24px;flex-wrap:wrap;font-size:.875rem}.footer-links a:hover{color:#b9c9dc}.footer-bottom{display:flex;justify-content:space-between;gap:25px;border-top:1px solid #41505e;padding-top:23px;margin-top:38px;font-size:.75rem;color:#b4c1ce}

/* Responsive composition. */
@media(max-width:1100px){.wrap{width:calc(100% - 64px)}.nav{gap:20px}.nav .contact{margin-left:0}.academy-hero{grid-template-columns:minmax(0,1fr) 270px;gap:36px;padding-top:55px}.academy-hero h1{font-size:clamp(3rem,5.5vw,4.6rem)}.portrait-mat{padding:24px 24px 0}.portrait-mat img{height:260px}.hero-author figcaption{padding:24px}.hero-kicker{display:block}.hero-kicker span{display:block;border:0;padding:0;margin-top:7px}.home-teaching,.personal-approach,.education-section{gap:50px}.library-editorial{gap:35px;grid-template-columns:minmax(0,1.1fr) minmax(0,1fr)}.problem-composition{grid-template-columns:135px minmax(0,1fr);gap:25px}.problem-composition h3{font-size:1.625rem}.library-paths{gap:22px}.home-journal{gap:45px;padding:38px}.page-grid,.article-layout{gap:45px}.library-shell{gap:35px;grid-template-columns:225px minmax(0,1fr)}.outcome-grid,.cohort-grid,.profi-grid,.document-grid{gap:24px}.outcome-number{font-size:3rem}.outcome-word{font-size:2rem}.teaser-evidence,.testimonial-feature .review-card{padding:30px}.teaser-evidence strong{font-size:2.3rem}.testimonial-feature .review-card blockquote{font-size:1.5rem}.document-caption{padding:23px}.document-grid{grid-template-columns:1fr 1fr}.resource-banner{gap:30px}.resource-banner .button{max-width:230px}.footer-top{align-items:flex-start}.footer-links{max-width:560px;justify-content:flex-end}}
@media(max-width:900px){.site-header{height:88px}.menu-toggle{display:block}.nav{display:none;position:absolute;top:87px;left:0;right:0;background:#fff;padding:25px 32px;border-bottom:1px solid var(--line);z-index:20;flex-direction:column;align-items:flex-start;gap:18px;font-size:1rem}.nav.open{display:flex}.nav .contact{font-size:1rem}.academy-hero{grid-template-columns:minmax(0,1fr) 230px;gap:28px}.academy-hero h1{font-size:clamp(2.5rem,5.25vw,3.6rem)}.hero-copy{font-size:1rem}.portrait-mat{padding:20px 20px 0}.portrait-mat img{height:230px}.hero-author figcaption{padding:20px}.author-name{font-size:1.25rem}.hero-subjects{gap:14px;margin-top:30px}.hero-subjects span+span{padding-left:14px}.credentials{gap:24px}.credential{padding-right:16px}.credential strong{font-size:1.35rem}.home-teaching{grid-template-columns:1fr;gap:32px}.home-section-intro{display:grid;grid-template-columns:1fr 1fr;gap:0 40px;align-items:start}.home-section-intro .eyebrow{grid-column:1/-1}.home-section-intro h2{grid-column:1;grid-row:2/4;margin:18px 0 0}.home-section-intro>p{grid-column:2;margin:18px 0 22px}.home-section-intro>.text-link{grid-column:2;justify-self:start}.teaching-row{padding:25px 0}.library-editorial{grid-template-columns:1fr 1fr;gap:30px}.problem-composition{display:block;padding:24px 0 5px}.problem-composition .board{width:150px;margin:0 0 25px}.problem-composition h3 br{display:none}.problem-composition h3{max-width:300px}.problem-composition p{margin:12px 0 22px}.library-feature .section-heading{align-items:flex-start}.library-feature .section-heading .button{max-width:200px}.library-paths{gap:16px 25px}.library-paths>span{width:100%}.personal-approach{gap:40px}.page-grid,.article-layout{grid-template-columns:minmax(0,1fr) 230px;gap:30px}.article-header{max-width:none}.library-shell{grid-template-columns:1fr}.library-filter{padding:22px}.library-filter h2{margin:0}.library-filter .filter-note{display:none}.library-filter label{margin-top:13px}.library-filter .filter-reset{margin-top:15px}.catalog-top{margin-top:5px}.path-detail{grid-template-columns:1fr;gap:40px}.path-aside{display:grid;grid-template-columns:1fr 1fr;gap:30px}.path-aside .aside-note+.aside-note{margin-top:0}.outcome-grid,.profi-grid{grid-template-columns:1fr}.outcome-card{padding:22px 0;display:grid;grid-template-columns:1fr 1.2fr;gap:0 35px}.outcome-card .tag{justify-self:start;grid-column:1}.outcome-card .outcome-number{grid-column:1;grid-row:2/4;margin:20px 0 0}.outcome-card h3{grid-column:2;grid-row:1}.outcome-card>p{grid-column:2}.outcome-card .evidence-note{margin:0;padding-top:15px}.outcome-word{font-size:2.4rem;line-height:1.3}.public-review{display:grid;grid-template-columns:1fr 1fr;gap:0 30px}.public-review .review-source{grid-column:1/-1}.public-review h4{grid-column:1}.public-review blockquote{grid-column:1}.public-review>p{grid-column:2;grid-row:2/4}.public-review .review-author{grid-column:1/-1;flex-direction:row;justify-content:space-between;width:100%}.portfolio-facts strong{font-size:1.625rem}.portfolio-facts{gap:25px}.private-reviews .review-featured{gap:0 35px;padding:32px}.private-reviews .review-featured blockquote{font-size:1.65rem}.resource-banner{display:block}.resource-banner .button{max-width:none;margin-top:24px}.journal-banner{display:block}.journal-banner .button{margin-top:26px}.contact-option{padding:30px 25px 30px 0}.contact-option+.contact-option{padding-left:25px}.contact-option h2{font-size:1.875rem!important}.footer-top{flex-direction:column}.footer-links{justify-content:flex-start;max-width:none}}
@media(max-width:650px){.wrap{width:calc(100% - 40px)}.brand-name{font-size:1.3rem}.brand-name>span{font-size:.6875rem}.nav{padding:25px 20px}.academy-hero{grid-template-columns:1fr;padding:38px 0 34px;gap:34px}.academy-hero h1{font-size:clamp(2.8rem,9.5vw,4.25rem);line-height:1.14;margin:24px 0 21px}.hero-kicker{font-size:.75rem}.hero-kicker span{margin-top:6px}.hero-subjects{margin-top:28px;font-size:.75rem}.academy-hero .actions{gap:22px}.academy-hero .button{padding:13px 18px}.hero-author{display:grid;grid-template-columns:120px minmax(0,1fr);align-items:center}.portrait-mat{padding:0}.portrait-mat img{width:120px;height:166px}.hero-author figcaption{padding:19px 22px}.author-name{font-size:1.375rem}.hero-author figcaption>a{margin-top:14px;padding-top:10px}.credentials{grid-template-columns:1fr;gap:0;padding:0}.credential{border:0;padding:18px 0;display:grid;grid-template-columns:1fr 1.2fr;gap:22px;align-items:center}.credential+.credential{border-top:1px solid var(--line)}.credential strong{font-size:1.3125rem;margin:0}.credential span{font-size:.75rem;line-height:1.6}.section{padding:56px 0}h2{font-size:2rem}.section-heading{display:block;margin-bottom:29px}.section-heading .eyebrow{margin-bottom:17px}.section-heading>p{margin-top:20px}.section-heading>.text-link{display:inline-block;margin-top:22px}.home-section-intro{display:block}.home-section-intro h2{margin:19px 0 23px}.home-section-intro>p{margin:0 0 22px}.home-teaching{gap:28px}.teaching-row{grid-template-columns:23px minmax(0,1fr) 16px;gap:16px;padding:24px 0}.teaching-row h3{font-size:1.375rem}.teaching-row p{font-size:1rem;line-height:1.65}.library-feature{padding:50px 0 28px}.library-feature .section-heading .button{max-width:none;margin-top:26px}.library-editorial{grid-template-columns:1fr;gap:30px}.featured-problem{padding:23px 0 27px}.problem-caption{font-size:.75rem;gap:10px}.problem-composition{display:grid;grid-template-columns:120px minmax(0,1fr);gap:23px;padding:25px 0 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/* Mathematical discovery — homepage, September 2026. */
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@media(max-width:650px){.math-opening{grid-template-columns:1fr;gap:29px;padding:33px 0 29px}.math-question h1{font-size:clamp(2.7rem,8.7vw,3.75rem);line-height:1.15;margin:20px 0}.math-question .eyebrow{font-size:.75rem;letter-spacing:.08em}.math-invitation{font-size:1rem}.quiet-link{margin-top:21px}.opening-challenge{padding:24px}.challenge-condition{font-size:1.0625rem;margin:18px 0}.challenge-prompt{font-size:1rem}.guess-option{min-height:58px;padding:12px 15px}.guess-option>span:first-child{font-size:1.4rem}.guess-option>span:last-child{font-size:.8125rem}.challenge-label{padding-bottom:15px}.math-explanation>summary{padding:21px 0}.explanation-content{grid-template-columns:1fr;padding-top:15px;gap:32px}.explanation-heading h2{font-size:2rem;margin:18px 0 23px}.percent-experiment{background:var(--soft);padding:23px}.price-track{background:#dfe5ed}.experiment-control{gap:10px}.price-stage-label{font-size:.8125rem;gap:12px}.price-stage-label strong{font-size:1.1875rem}.stage-calculation{font-size:.75rem}.experiment-conclusion{font-size:.9375rem}.experiment-equation{font-size:.9375rem;line-height:1.8}.algebra-insight>summary{line-height:1.6}.algebra-insight .insight-formula{font-size:1.4rem}.explanation-next{display:block}.explanation-next .text-link{display:inline-block;margin-top:20px}.math-purpose{grid-template-columns:1fr;gap:19px;padding:32px 0}.math-purpose>.eyebrow{padding:0}.math-purpose>p:last-child{font-size:1.1875rem;line-height:1.7}.discovery-grid{grid-template-columns:1fr;gap:37px}.discovery-card{padding-top:18px}.discovery-equation,.domino-proof,.search-proof{font-size:2rem;min-height:0;padding:25px 0;gap:12px}.discovery-card h3{font-size:1.55rem}.discovery-card>p{margin:16px 0 18px}.discovery-bottom{font-size:.8125rem}.math-learning{padding:47px 0}.math-learning>.wrap{grid-template-columns:1fr;gap:32px}.math-learning-intro h2{font-size:2rem;margin:20px 0}.learning-options h3{font-size:1.4rem}.math-journal{display:block;padding:49px 0}.math-journal h2{font-size:2rem}.math-journal .button{margin-top:26px}.project-author{padding:27px 0 32px;gap:17px}.project-author img{width:40px;height:54px}.project-author>p{font-size:.75rem;flex:1}.project-author>div{margin:0;width:100%;gap:14px 20px;font-size:.8125rem}}

/* A visual experiment, an editorial game feature. */
.chaos-opening{display:grid;grid-template-columns:1fr 1.08fr;gap:60px;align-items:center;padding:55px 0 40px}.chaos-intro h1{font:500 clamp(2.8rem,4.8vw,4.5rem)/1.13 var(--display);letter-spacing:-.065em;margin:26px 0}.chaos-intro h1 em{font-family:var(--serif);font-weight:400;color:#345f87;letter-spacing:-.045em}.chaos-lead{font-size:1.125rem;line-height:1.8}.chaos-invite{max-width:400px;color:var(--muted);font-size:1rem;margin-top:16px}.chaos-rule{list-style:none;counter-reset:rule;padding:0;margin:28px 0 0;font-size:1rem}.chaos-rule li{counter-increment:rule;margin-top:11px;display:flex;gap:15px;align-items:baseline}.chaos-rule li:before{content:'0' counter(rule);color:#90724f;font-size:.75rem;font-variant-numeric:tabular-nums}.chaos-intro .quiet-link{margin-top:25px}.chaos-workbench{background:#f4f5f5;border:1px solid #e0e5e9;padding:22px 26px 18px;min-width:0}.chaos-topline{display:flex;justify-content:space-between;gap:15px;font-size:.75rem;color:var(--muted)}.chaos-stage{position:relative}.chaos-stage canvas{width:100%;height:auto;aspect-ratio:640/520;display:block;cursor:crosshair}.chaos-canvas-label{display:block;text-align:center;font-size:.75rem;color:var(--muted);margin-top:-20px;margin-bottom:22px}.chaos-readout{border-top:1px solid #d6dee4;padding-top:16px;display:flex;justify-content:space-between;gap:22px;align-items:center;font-size:.8125rem;min-height:58px}.chaos-readout strong{font:500 1.35rem var(--display);font-variant-numeric:tabular-nums;color:var(--ink)}.chaos-readout>span:first-child{white-space:nowrap}.chaos-readout>span:last-child{color:var(--muted);max-width:245px;text-align:right}.chaos-controls{display:flex;gap:17px;align-items:center;margin-top:16px}.chaos-controls .button{min-height:50px;padding:15px 20px;font-size:.875rem;flex:1}.chaos-step{border:0;background:none;color:var(--ink);font-size:.875rem;padding:14px 0;white-space:nowrap;border-bottom:1px solid #c6ced6}.chaos-tools{display:flex;flex-wrap:wrap;gap:4px 18px;margin-top:12px}.chaos-tools button{border:0;background:none;font-size:.75rem;color:var(--muted);padding:8px 0;text-decoration:underline;text-underline-offset:4px}.chaos-help{color:var(--muted);font-size:.75rem;line-height:1.6;margin-top:4px}.chaos-secret{border-top:1px solid var(--line);border-bottom:1px solid var(--line);scroll-margin-top:30px}.chaos-secret>summary{display:flex;justify-content:space-between;gap:20px;list-style:none;padding:25px 0;font-size:1rem;cursor:pointer}.chaos-secret>summary::-webkit-details-marker{display:none}.chaos-secret>summary>span:last-child{font-size:1.5rem;line-height:1}.chaos-secret[open]>summary>span:last-child{transform:rotate(45deg)}.chaos-secret-content{display:grid;grid-template-columns:1.1fr 1fr;gap:25px 80px;padding:25px 0 40px}.chaos-secret-content h2{margin:20px 0 25px;font-size:2.4rem}.chaos-secret-content p:not(.eyebrow){color:var(--muted);margin-top:17px}.chaos-proof svg{max-height:330px;width:100%;display:block}.chaos-proof>p{text-align:center;font-size:.875rem!important}.chaos-afterthought{grid-column:1/-1;border-top:1px solid var(--line);padding-top:25px;max-width:880px}.sigma-feature{display:grid;grid-template-columns:1fr 1fr;gap:75px;background:var(--navy);color:#f6f7fa;margin-top:55px;padding:55px}.sigma-feature .eyebrow{color:#b8c8d9}.sigma-feature h2{font-size:clamp(2.3rem,3.5vw,3.3rem);line-height:1.15;margin:25px 0;letter-spacing:-.05em}.sigma-feature h2 em{font-family:var(--serif);font-weight:400;color:#cfb699}.sigma-feature-intro>p:not(.eyebrow){color:#b8c8d9;max-width:425px;font-size:1rem}.sigma-feature .button{background:#f5f5f2;color:var(--navy);margin-top:29px;border-color:#f5f5f2}.sigma-feature-story{border-left:1px solid #51647e;padding-left:55px;display:flex;flex-direction:column;justify-content:center}.sigma-wordmark{font:600 2rem var(--display);letter-spacing:.04em}.sigma-wordmark>span{font-size:.6875rem;letter-spacing:.25em;display:block;color:#b8c8d9;margin-top:3px}.sigma-life{display:flex;justify-content:space-between;font-size:.8125rem;color:#b8c8d9;margin:42px 0 9px}.sigma-start-capital{font:400 clamp(2.3rem,3.7vw,3.7rem) var(--display);letter-spacing:-.04em;font-variant-numeric:tabular-nums}.sigma-start-capital span{font-size:1.7rem;color:#cfb699}.sigma-feature-story>p:not(.sigma-start-capital){font-size:1rem;color:#b8c8d9;margin-top:10px}.sigma-decision{display:flex;justify-content:space-between;gap:10px;border-block:1px solid #51647e;margin:27px 0 20px;padding:20px 0;font-size:.875rem}.sigma-decision:hover{color:#cfb699}.sigma-feature-note{font-size:.75rem;color:#b8c8d9}.experiment-breadcrumb{margin-top:30px}.experiment-return{padding:35px 0 60px}.experiment-breadcrumb+.math-opening{padding-top:35px}
@media(max-width:1000px){.chaos-opening{gap:35px}.chaos-intro h1{font-size:3rem}.chaos-workbench{padding:20px}.sigma-feature{gap:40px;padding:40px}.sigma-feature-story{padding-left:35px}.chaos-controls{gap:12px}.chaos-controls .button{padding-inline:12px}.chaos-topline{font-size:.6875rem}.chaos-secret-content{gap:30px}}
@media(max-width:720px){.chaos-opening{grid-template-columns:1fr;gap:28px;padding:35px 0 28px}.chaos-intro h1{font-size:clamp(2.8rem,9vw,4rem);margin:20px 0}.chaos-intro .eyebrow{font-size:.75rem}.chaos-lead{font-size:1rem}.chaos-invite{margin-top:12px}.chaos-rule{margin-top:20px}.chaos-intro .quiet-link{margin-top:20px}.chaos-workbench{padding:18px}.chaos-stage canvas{max-height:390px;aspect-ratio:640/520}.chaos-topline{font-size:.6875rem}.chaos-canvas-label{font-size:.6875rem;margin-top:-15px;margin-bottom:17px}.chaos-readout{font-size:.75rem;gap:15px}.chaos-readout strong{font-size:1.2rem}.chaos-controls .button{font-size:.8125rem}.chaos-step{font-size:.8125rem}.chaos-secret>summary{font-size:.9375rem;line-height:1.6;align-items:center}.chaos-secret-content{grid-template-columns:1fr;padding:15px 0 30px}.chaos-secret-content h2{font-size:2rem}.chaos-proof svg{max-height:250px}.chaos-afterthought{margin-top:0!important}.sigma-feature{grid-template-columns:1fr;margin-top:35px;padding:28px;gap:35px}.sigma-feature h2{font-size:2.6rem;margin:20px 0}.sigma-feature-story{border-left:0;border-top:1px solid #51647e;padding:28px 0 0}.sigma-wordmark{font-size:1.5rem}.sigma-life{margin-top:25px}.sigma-start-capital{font-size:3.1rem}.sigma-feature .button{width:100%;justify-content:space-between}.sigma-feature-note{font-size:.6875rem}.math-purpose{padding-top:30px}}

/* Interactive puzzle collection. */
.puzzle-head{max-width:910px;padding-bottom:35px}.puzzle-head h1{font-size:clamp(2.4rem,4.6vw,4.4rem);line-height:1.16;letter-spacing:-.055em}.puzzle-head .lead{max-width:790px;font-size:1.125rem}.puzzle-panel{background:#f2f5f5;border:1px solid #dce3e5;padding:35px 45px;max-width:1020px;margin:0 auto 45px;min-width:0}.puzzle-toolbar{display:flex;justify-content:space-between;align-items:center;gap:20px}.puzzle-levels,.hat-perspectives{display:flex;gap:8px;flex-wrap:wrap}.puzzle-levels button,.hat-perspectives button,.puzzle-answers button{border:1px solid #bdcad5;background:white;color:var(--ink);padding:12px 20px;min-height:44px;font-size:.875rem}.puzzle-levels button[aria-pressed=true],.hat-perspectives button[aria-pressed=true],.puzzle-answers button[aria-pressed=true]{background:var(--navy);color:white;border-color:var(--navy)}.puzzle-counter{font-size:.875rem;white-space:nowrap}.puzzle-counter strong{font:500 1.8rem var(--display);margin-right:5px}.frog-direction{display:flex;justify-content:space-between;margin-top:30px;font-size:.8125rem;color:var(--muted)}.frog-board{position:relative;width:100%;height:195px;--stones:7;margin:0 auto 15px;border-bottom:1px solid #b2c8c8}.frog-stone{position:absolute;bottom:19px;width:calc(100% / var(--stones) - 8px);height:27px;background:#d9e4e1;border:1px solid #b6ceca;border-radius:50%;transform:translateX(-50%);font-size:.6875rem;line-height:25px;color:#557775;text-align:center}.frog-token{position:absolute;bottom:47px;width:calc(100% / var(--stones) - 8px);max-width:75px;min-height:75px;padding:0 2px;border:0;background:none;transform:translateX(-50%);color:#4f8274;cursor:pointer;z-index:2}.frog-token.sand{color:var(--frog-indigo,#5269a7)}.frog-token svg{width:100%;height:auto;display:block}.frog-token>span{font-size:1rem;line-height:1;display:block;color:var(--muted)}.frog-token:hover{filter:brightness(1.1)}.frog-token.hinted{outline:2px dashed #907451;outline-offset:4px;border-radius:4px}.frog-board.won{border-color:#57806f}.frog-board.won .frog-stone{background:#cbddd4}.puzzle-feedback{font-size:1rem;line-height:1.65;min-height:27px;color:var(--blue);margin:18px 0}.puzzle-actions{display:flex;gap:15px;flex-wrap:wrap;align-items:center;margin-top:25px}.puzzle-actions .button{min-height:48px;padding:13px 22px;font-size:.875rem}.puzzle-text-button{border:0;border-bottom:1px solid #9caeba;background:none;color:var(--muted);font-size:.875rem;padding:12px 0}.puzzle-fine{font-size:.8125rem!important;line-height:1.6;color:var(--muted);margin-top:20px}.puzzle-reading{max-width:800px;margin:0 auto 45px;font-size:1.0625rem;line-height:1.85}.puzzle-reading h2{font-size:1.8rem;margin-bottom:20px}.puzzle-reading ol{padding-left:24px;margin-bottom:30px}.puzzle-reading li{margin-bottom:10px}.puzzle-reading>p+p{margin-top:15px}.puzzle-details{border-top:1px solid var(--line)}.puzzle-details:last-of-type{border-bottom:1px solid var(--line)}.puzzle-details>summary{display:flex;justify-content:space-between;gap:20px;cursor:pointer;list-style:none;padding:22px 0;font-size:1rem;color:var(--ink);line-height:1.6}.puzzle-details>summary::-webkit-details-marker{display:none}.puzzle-details[open]>summary>span{transform:rotate(45deg)}.puzzle-details>.prose{padding:0 0 25px;font-size:1rem}.puzzle-details .prose p+p{margin-top:16px}.puzzle-reading .source-note{font-size:.8125rem;line-height:1.7;margin-top:27px}.source-note a{text-decoration:underline;text-underline-offset:3px}.puzzle-next{display:flex;justify-content:space-between;flex-wrap:wrap;gap:20px;border-top:1px solid var(--line);padding:30px 0 65px}.puzzle-card-symbol{min-height:145px;display:flex;align-items:center;font:400 2rem var(--display);letter-spacing:.02em;color:#547a7c}.puzzle-condition{max-width:900px}.puzzle-condition p{font-size:1rem;color:var(--muted);line-height:1.8}.hat-scene{display:grid;grid-template-columns:1fr 1fr 1fr 20px 1fr;align-items:end;gap:22px;margin:45px auto 20px;max-width:770px}.hat-person{min-width:0;text-align:center}.hat-shape{height:52px;width:60px;margin:0 auto;position:relative;background:var(--navy);border:2px solid var(--navy);border-radius:18px 18px 0 0}.hat-shape:after{content:'';position:absolute;bottom:-7px;left:-13px;width:82px;height:8px;background:var(--navy);border-radius:3px}.hat-shape.light{background:white}.hat-shape.light:after{background:white;border:2px solid var(--navy);box-sizing:border-box}.hat-shape>span{display:none}.hat-head{width:44px;height:43px;border:1px solid #b4c0ca;border-top:0;background:#e3e7e9;border-radius:0 0 45% 45%;margin:5px auto 18px}.hat-number{display:block;font:500 1.1rem var(--display)}.hat-gaze{display:block;font-size:.75rem;color:var(--muted);margin-top:7px}.hat-wall{height:170px;border-left:2px solid #a0afb9;border-right:2px solid #a0afb9;background:repeating-linear-gradient(135deg,#e0e6e9 0 6px,transparent 6px 13px)}.hat-person.unknown .hat-shape{background:#e3e8eb;border-color:#a2b0ba}.hat-person.unknown .hat-shape:after{background:#e3e8eb;border:2px solid #a2b0ba;box-sizing:border-box}.hat-person.unknown .hat-shape>span{display:block;color:#677b8d;font-size:1.5rem;line-height:45px}.puzzle-prompt{font:500 1.25rem/1.6 var(--display);margin:25px 0 18px}.puzzle-answers{display:flex;gap:12px;flex-wrap:wrap}.puzzle-answers button{min-width:85px;font-size:1.125rem}.coin-outcomes{display:grid;grid-template-columns:repeat(4,1fr);gap:22px;border-block:1px solid var(--line);padding:30px 0;margin:25px 0}.coin-outcome{display:flex;flex-direction:column;align-items:center;gap:13px;min-width:0}.coin-pair{display:flex;gap:7px}.coin-pair i{display:grid;place-items:center;width:44px;height:44px;border:1px solid #ae987c;border-radius:50%;font:400 1.15rem var(--serif);color:#86674d;background:#eee6da}.coin-outcome>span:nth-child(2){font-size:.8125rem;text-align:center;color:var(--muted)}.coin-outcome strong{font:500 1.8rem var(--display);font-variant-numeric:tabular-nums}.coin-track{height:5px;background:#dbe2e6;width:100%;margin-top:7px}.coin-track>span{height:100%;width:0;display:block;background:var(--navy);transition:width .3s}.puzzle-reading .prose{max-width:100%}
@media(max-width:720px){.puzzle-head{padding-bottom:27px}.puzzle-head h1{font-size:2.6rem}.puzzle-head .lead{font-size:1rem;line-height:1.8}.puzzle-panel{padding:22px 18px;margin-bottom:30px}.puzzle-levels button{padding:9px 14px}.puzzle-counter{font-size:.8125rem}.puzzle-counter strong{font-size:1.5rem}.frog-board{height:140px}.frog-token{min-height:64px;width:calc(100% / var(--stones) - 4px);padding:0;bottom:43px}.frog-stone{width:calc(100% / var(--stones) - 4px);bottom:16px;height:23px;line-height:22px}.frog-token>span{font-size:.875rem}.frog-direction{font-size:.75rem;margin-top:25px}.puzzle-actions{gap:12px}.puzzle-actions .button{padding:12px 14px}.puzzle-feedback{font-size:.9375rem}.puzzle-reading{font-size:1rem;margin-bottom:30px}.puzzle-reading h2{font-size:1.6rem}.puzzle-details>summary{font-size:.9375rem}.puzzle-next{padding-bottom:45px}.hat-perspectives{gap:7px}.hat-perspectives button{font-size:.75rem;padding:10px}.hat-scene{gap:8px;grid-template-columns:1fr 1fr 1fr 10px 1fr;margin-top:35px}.hat-shape{width:35px;height:33px;border-radius:12px 12px 0 0}.hat-shape:after{width:47px;left:-8px;height:6px;bottom:-5px}.hat-head{width:29px;height:30px;margin-top:4px;margin-bottom:12px}.hat-gaze{font-size:.625rem;line-height:1.6}.hat-wall{height:135px}.hat-number{font-size:.9375rem}.hat-person.unknown .hat-shape>span{font-size:1.125rem;line-height:30px}.puzzle-answers{gap:8px}.puzzle-answers button{min-width:54px;padding:12px 17px;font-size:1rem}.coin-outcomes{grid-template-columns:1fr 1fr;gap:25px 22px}.coin-pair i{width:38px;height:38px}.puzzle-card-symbol{min-height:120px;font-size:1.85rem}.chaos-intro .chaos-rule{display:none}.chaos-intro .chaos-lead{max-width:350px}.chaos-invite{margin-top:12px}.chaos-intro .quiet-link{margin-top:14px}.chaos-stage canvas{max-height:320px}}
@media(prefers-reduced-motion:reduce){.coin-track>span{transition:none}}
@media(max-width:720px){.chaos-workbench{display:flex;flex-direction:column}.chaos-topline{order:0}.chaos-controls{order:1;margin:18px 0 0}.chaos-stage{order:2}.chaos-readout{order:3}.chaos-tools{order:4}.chaos-help{order:5}.chaos-stage canvas{aspect-ratio:640/500}.chaos-canvas-label{margin-bottom:17px}.chaos-invite{line-height:1.65}.chaos-intro .quiet-link{display:none}}
.breadcrumbs>span{margin-inline:8px}

/* Task bank: quiet editorial index and diagrams that carry the argument. */
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';color:#607e9f}.birthday-controls{display:grid;grid-template-columns:1fr 200px;align-items:center;gap:20px 40px}.birthday-controls label{font-size:19px}.birthday-controls input{grid-row:2;width:100%;accent-color:#294e7a;min-height:28px}.birthday-theory{grid-column:2;grid-row:1/3;display:flex;flex-direction:column;gap:6px}.birthday-theory strong{font-size:44px;color:#244f7e;font-family:'Manrope',sans-serif}.birthday-theory span,.birthday-theory small{font-size:14px}.birthday-room{display:grid;grid-template-columns:repeat(auto-fill,minmax(70px,1fr));gap:10px;margin:28px 0}.birthday-person{border:2px solid #d8e2ec;border-radius:8px;padding:10px 6px;display:flex;flex-direction:column;text-align:center;gap:6px;background:#fff}.birthday-person small{font-size:12px;color:#56728f}.birthday-person strong{font-size:14px}.birthday-person.matched{border-color:#376c5b;background:#e2f0e8}.puzzle-panel button:focus-visible,.save-task:focus-visible{outline:3px solid #bf8e49;outline-offset:4px}button[hidden],a[hidden],[hidden]{display:none!important}@keyframes disk-appear{from{transform:translateY(-8px);opacity:.5}to{transform:translateY(0);opacity:1}}
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@media(prefers-reduced-motion:reduce){.tower-disc,.monty-door,.stat-track span{animation:none;transition:none}}
[data-library-page] .compact-head{padding-top:42px;padding-bottom:26px}[data-library-page] .compact-head h1{font-size:clamp(32px,4vw,52px);margin:15px 0}[data-library-page] .compact-head .lead{font-size:18px;max-width:760px}[data-library-page] .library-tabs{margin-top:23px}.catalog-more{margin-top:28px}.library-filter{align-self:start}.library-filter select{width:100%}[data-library-page] .daily-discovery{padding:23px 30px}[data-library-page] .daily-discovery h2{font-size:26px;margin:8px 0}[data-library-page] .daily-discovery p{font-size:15px}.catalog-item h2{overflow-wrap:anywhere}
@media(max-width:700px){[data-library-page] .compact-head{padding-top:25px;padding-bottom:20px}[data-library-page] .compact-head .lead{font-size:16px;line-height:1.6}[data-library-page] .daily-discovery{padding:20px;gap:14px}[data-library-page] .daily-discovery h2{font-size:21px}[data-library-page] .daily-discovery p{display:none}[data-library-page] .daily-discovery .button{padding:12px 18px;min-height:42px}[data-library-page] .library-return{font-size:13px;margin-bottom:5px}[data-library-page] .content-section{padding-top:20px}.catalog-top{flex-wrap:wrap;gap:8px}}
.person-figure svg{display:block;width:30px;height:42px;margin:auto}.bridge-water{font-family:monospace}
@media(max-width:700px){.bridge-bank>div{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));align-content:start;gap:6px}.bridge-person{min-width:0;padding:9px 2px;min-height:90px}.bridge-person strong{font-size:13px;white-space:nowrap}.person-figure{margin-bottom:8px}.person-figure svg{width:24px;height:36px}.bridge-scene{padding-left:8px;padding-right:8px;grid-template-columns:1fr 24px 1fr;gap:6px}}
/* Hands-on experiments: water, rolling motion, tiling and permutations. */
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@media(max-width:700px){.jug-scene{gap:20px}.jug-vessel{height:190px}.jug-vessel>span{font-size:21px}.jug-controls .button{font-size:14px;padding:12px 10px}.jug-station h2{font-size:18px}.rolling-scene{max-width:330px}[data-rolling] select{margin:9px 0 0;display:block;width:100%}[data-rolling] .puzzle-toolbar{align-items:flex-start}.locker-grid{gap:3px}.locker{font-size:11px;padding:2px;min-height:24px}.locker small{font-size:8px;right:1px;top:-2px}.domino-board{gap:2px}.domino-tray{flex-shrink:0}.domino-cell.occupied{box-shadow:inset 0 0 0 2px #a8854b}}
@media(prefers-reduced-motion:reduce){.jug-water,.tile,.locker{transition:none}}

/* Original illustrations inside the curated solutions. */
.math-figure svg{display:block;width:min(100%,420px);max-height:350px;margin:18px auto}
.math-figure>p{font-size:14px;line-height:1.65;color:var(--muted);margin-top:18px}
.idea-flow strong{overflow-wrap:anywhere}
@media(max-width:600px){.locker{font-size:12px}.idea-flow{grid-template-columns:1fr}.idea-flow>div{min-width:0}}
.domino-cell.occupied{background:var(--piece-color);border:2px solid #fff;color:#233e59;position:relative;z-index:1}
.domino-cell.join-right{border-right:0;border-radius:7px 0 0 7px}.domino-cell.join-left{border-left:0;border-radius:0 7px 7px 0}
.domino-cell.join-down{border-bottom:0;border-radius:7px 7px 0 0}.domino-cell.join-up{border-top:0;border-radius:0 0 7px 7px}
.domino-board.colored .domino-cell.occupied{background:var(--piece-color)}
.domino-board.colored .domino-cell.occupied.dark{background:var(--piece-color);box-shadow:inset 0 0 0 3px #244967}
.domino-board{grid-template-rows:repeat(8,minmax(0,1fr))}
.domino-cell{display:grid;place-items:center;line-height:1;overflow:hidden}
.domino-cell.occupied{box-shadow:none}
@media(max-width:700px){[data-domino] .puzzle-toolbar{display:grid;grid-template-columns:82px minmax(0,1fr);gap:12px}[data-domino-color]{grid-column:1/-1;justify-content:center}[data-domino] .puzzle-toolbar .button{padding:12px;min-width:0}}
.article-layout>.prose{min-width:0}
.idea-table{max-width:100%;overflow-x:auto}
@media(max-width:600px){.idea-table th,.idea-table td{padding:9px 6px;font-size:13px}}

/* Olympiad archive: full variants and independently addressable explanations. */
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var(--line);background:var(--soft)}.archive-empty h2{font-size:25px}.archive-empty p{max-width:680px;margin:18px 0;line-height:1.8}.archive-empty .button{margin:10px 0}.archive-guide{display:grid;grid-template-columns:1fr 1.2fr;gap:80px;padding:50px 0;border-block:1px solid var(--line)}.archive-guide h2{font:400 30px/1.35 var(--display);margin-top:22px;letter-spacing:-.04em}.archive-guide ol{padding-left:22px;line-height:1.9;font-size:15px}.archive-guide li+li{margin-top:16px}.archive-official{padding:56px 0}.archive-official>h2{margin:22px 0;font:400 32px var(--display)}.archive-official>p{max-width:740px;color:var(--muted);line-height:1.8}.archive-source-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:24px;margin:32px 0}.archive-source-grid>div{padding-top:18px;border-top:1px solid var(--line)}.archive-source-grid h3{font-size:16px;line-height:1.5;margin-bottom:14px}.archive-source-grid a{font-size:13px;color:var(--blue)}.archive-bottom-note{display:flex;align-items:center;justify-content:space-between;gap:40px;border-top:1px solid var(--line);padding:28px 0 55px;font-size:14px;line-height:1.8}.archive-bottom-note p{max-width:600px}.archive-bottom-note a{white-space:nowrap;color:var(--blue)}.archive-variant-layout{display:grid;grid-template-columns:minmax(0,1fr) 255px;gap:75px}.archive-variant-layout>section{min-width:0}.archive-reading-note{font-size:15px;line-height:1.8;color:var(--muted);margin-bottom:30px}.archive-condition{padding:30px 0;border-top:1px solid var(--line);scroll-margin-top:30px}.archive-condition-top{display:flex;align-items:center;gap:18px;font-size:12px;color:#3b7050}.archive-condition h2{font:500 25px/1.4 var(--display);letter-spacing:-.04em;margin:20px 0}.archive-condition h2 a:hover{color:var(--blue)}.archive-problem{font-size:17px;line-height:1.9;overflow-wrap:anywhere}.archive-problem p+p{margin-top:16px}.archive-condition>.text-link{display:inline-block;margin-top:23px;font-size:14px}.archive-variant-layout .aside-note nav{display:grid;gap:13px}.archive-variant-layout .aside-note nav a{line-height:1.6;font-size:13px}.archive-variant-layout .aside-note h2,.olympiad-task .aside-note h2{font-size:15px;font-weight:600;margin-bottom:20px}.archive-editorial-note{border-left:3px solid #ab8040;background:#fcf7ec;padding:20px 23px;margin:22px 0;font-size:14px;line-height:1.85;color:#59472e}.archive-editorial-note p{font-size:14px}.archive-proof>section{margin-bottom:32px}.archive-proof-number{font-size:11px;text-transform:uppercase;letter-spacing:.1em;color:var(--muted);margin-bottom:9px}.archive-proof h3{margin:0 0 17px;font-size:21px}.archive-proof p{overflow-wrap:anywhere}.archive-answer{background:#eef4f1;border-left:3px solid #3e6d51;padding:20px 23px;margin-top:30px}.archive-answer>strong{font-size:12px;text-transform:uppercase;letter-spacing:.1em;color:#3e6d51}.archive-answer p{margin-top:10px}.archive-formula{background:var(--soft);padding:18px 22px;margin:22px 0;font:20px/1.8 var(--serif);overflow-wrap:anywhere}.archive-next{display:flex;justify-content:space-between;gap:25px;margin:32px 0;padding:24px 0;border-block:1px solid var(--line);font-size:14px}.archive-ask{font-size:14px;line-height:1.9;margin:35px 0}.archive-ask a{color:var(--blue)}.archive-figure{margin:25px 0;background:#f5f7fa;border:1px solid var(--line);padding:20px}.archive-figure svg{display:block;width:100%;height:auto;max-height:390px}.archive-figure figcaption{font-size:12px;line-height:1.8;color:var(--muted);margin-top:15px}.archive-mini-table{width:100%;border-collapse:collapse;font-size:14px;margin:20px 0}.archive-mini-table th,.archive-mini-table td{padding:12px;border:1px solid var(--line);text-align:left}.archive-mini-table th{background:var(--soft)}
@media(min-width:851px){.nav{gap:19px;font-size:13px}.nav .contact{margin-left:0}}
@media(max-width:1100px){.archive-filter{grid-template-columns:1fr 1fr 1.5fr}.archive-variants{gap:18px}.archive-variant{padding:20px}.archive-variant h2{font-size:22px}.archive-variant-top{align-items:flex-start}.archive-status{font-size:10px;line-height:1.5}.archive-guide{gap:40px}.archive-variant-layout{gap:40px;grid-template-columns:minmax(0,1fr) 210px}}
@media(max-width:850px){.archive-variants{grid-template-columns:1fr}.archive-variant{padding:25px}.archive-variant h2{font-size:27px}.archive-variant>p:not(.archive-meta){max-width:620px}.archive-meta{margin-top:15px}.archive-variant-bottom{flex-direction:row;flex-wrap:wrap;justify-content:space-between;align-items:center}.archive-guide{grid-template-columns:1fr;gap:25px}.archive-source-grid{grid-template-columns:1fr 1fr}.archive-variant-layout{grid-template-columns:1fr;gap:25px}.archive-variant-layout>.article-side{order:-1;position:static}.archive-variant-layout>.article-side .aside-note{display:none}.archive-bottom-note{display:block}.archive-bottom-note a{display:inline-block;margin-top:20px}.archive-filter{grid-template-columns:1fr 1fr}.archive-head h1{font-size:40px}}
@media(max-width:500px){.archive-head h1{font-size:34px}.archive-head .lead{font-size:16px}.archive-edition{gap:13px 22px;font-size:12px}.archive-edition strong{font-size:21px}.archive-edition>span:last-child{width:100%}.archive-filter{padding:17px;gap:14px 10px}.archive-filter>div:nth-child(3){grid-column:1/-1;grid-row:2}.archive-filter .filter-reset{grid-column:1/-1;height:35px}.archive-filter select{font-size:13px;padding:0 8px}.archive-results-line{font-size:12px;flex-wrap:wrap;gap:12px}.archive-variant{padding:23px}.archive-variant h2{font-size:25px}.archive-guide h2{font-size:27px}.archive-guide{padding:35px 0}.archive-source-grid{grid-template-columns:1fr}.archive-empty{padding:24px}.archive-empty h2{font-size:23px}.archive-condition h2{font-size:23px}.archive-problem{font-size:16px;line-height:1.85}.archive-proof h3{font-size:20px}.archive-editorial-note{padding:17px}.archive-figure{padding:10px}.archive-mini-table th,.archive-mini-table td{padding:8px;font-size:12px}.archive-variant-layout .content-section{padding-top:20px}}
@media print{.archive-filter,.archive-results-line,.archive-guide,.archive-official,.archive-bottom-note,.archive-reading-note,.archive-task-index,.task-progress-tools,.archive-next,.archive-ask,.after-solution,.archive-condition>.text-link{display:none!important}.archive-variant-layout{display:block}.archive-condition{break-inside:avoid}.archive-condition h2{font-size:15pt}.archive-problem{font-size:12pt}.archive-figure{max-width:480px;break-inside:avoid}.archive-edition{display:none}.archive-editorial-note{font-size:10pt;background:white}.olympiad-task #insight{display:none!important}}
.archive-flow{display:grid;gap:14px}.archive-flow>div{display:grid;grid-template-columns:minmax(120px,1fr) minmax(0,1.2fr);gap:20px;align-items:center;padding-bottom:14px;border-bottom:1px solid var(--line)}.archive-flow>div:last-child{border:0;padding-bottom:0}.archive-flow strong{font:500 20px/1.5 var(--display);overflow-wrap:anywhere}.archive-flow span{font-size:14px;line-height:1.7;color:var(--muted)}.archive-number-families{display:grid;grid-template-columns:repeat(2,1fr);gap:22px}.archive-number-families p{font-size:13px!important;margin:5px 0!important}.archive-number-families table{margin:0}.archive-number-families .archive-sum{border:0;background:transparent;color:var(--muted);font-size:12px}.archive-equation{display:flex;align-items:center;justify-content:center;flex-wrap:wrap;gap:14px;font:21px/1.7 var(--serif);padding:25px 0}.archive-fraction{display:inline-flex;flex-direction:column;text-align:center}.archive-fraction>span:first-child{border-bottom:1px solid;padding:0 5px 6px}.archive-fraction>span:last-child{padding:6px 5px 0}.archive-absolute{padding:5px 8px;border-inline:1px solid}.archive-traffic{padding:22px;background:#f2f5f8;border:1px solid var(--line);margin-bottom:28px}.archive-traffic>p{font-size:14px!important;line-height:1.8!important}.archive-traffic>label{display:block;font-size:14px;font-weight:500;margin:22px 0 12px}.archive-traffic>input[type=range]{width:100%;accent-color:var(--blue);height:30px}.archive-time-axis{display:flex;justify-content:space-between;font-size:11px;color:var(--muted);margin-top:20px}.archive-signal-row{margin:12px 0 22px}.archive-signal-row>strong{display:block;font-size:12px;font-weight:400;margin-bottom:8px}.archive-signal-row>p{font-size:12px!important;line-height:1.6!important;margin-top:8px!important}.archive-signal{height:32px;position:relative;border:1px solid #c7d1da;overflow:hidden}.archive-signal>span{position:absolute;top:5px;height:20px;background:#243b57;border:2px solid white;min-width:2px}.archive-road{height:24px;background:#dfe6ed;position:relative;margin-top:25px;border-block:2px solid #aab8c7}.archive-crosswalk{position:absolute;top:0;bottom:0;background:repeating-linear-gradient(90deg,#fff 0px,#fff 4px,#97aabd 4px,#97aabd 8px)}.archive-crosswalk.first{left:23.8095%;width:14.2857%}.archive-crosswalk.second{left:95.238%;width:4.762%}.archive-rider{position:absolute;left:0;top:-6px;color:#1d448c;font-size:27px;transform:translateX(-50%);line-height:30px}.archive-road-labels{display:flex;justify-content:space-between;font-size:11px;margin:12px 0 22px;color:var(--muted)}.archive-traffic .button{font-size:13px;padding:12px 17px}.archive-traffic [data-traffic-clock]{font-variant-numeric:tabular-nums;min-width:100px}.archive-traffic [data-traffic-result]{min-height:48px;padding:10px 0;color:#34583e}.archive-traffic [data-traffic-result][data-pass=false]{color:#804334}
@media(max-width:500px){.archive-flow>div{grid-template-columns:1fr;gap:5px}.archive-flow strong{font-size:18px}.archive-flow span{font-size:13px}.archive-traffic{padding:16px}.archive-equation{font-size:17px;gap:10px}.archive-number-families{gap:12px}.archive-traffic .source-note{font-size:11px!important}}
.olympiad-archive .button.outline,.olympiad-task .button.outline{color:var(--ink);background:transparent}.olympiad-archive .button.outline:hover,.olympiad-task .button.outline:hover{color:#fff;background:var(--navy);border-color:var(--navy)}
.archive-club{padding:24px;border:1px solid var(--line);background:#f3f6fa;border-radius:8px;margin:24px 0}.archive-club label{display:block;font-weight:600}.archive-club input{width:100%;margin:20px 0;accent-color:#264e7a}.archive-club-bars>div{display:grid;grid-template-columns:24px 1fr 38px;gap:12px;align-items:center;margin:12px 0}.archive-club-bars>div>div{height:25px;background:#e4eaf0;border-radius:3px;overflow:hidden}.archive-club-bars span{display:block;height:100%;background:#426d98;transition:width .25s ease}.archive-club-bars>div:nth-child(2) span{background:#b79663}.archive-club-bars>div:nth-child(3) span{background:#6f9385}@media(prefers-reduced-motion:reduce){.archive-club-bars span{transition:none}}

/* Contact: a quiet, focused conversation form. */
.contact-head h1 span{color:var(--blue,#294ddd)}.contact-layout{display:grid;grid-template-columns:minmax(0,1.65fr) minmax(250px,.8fr);gap:72px;align-items:start;padding-top:0}.contact-card{background:#fff;border:1px solid #dce1e8;border-radius:8px;padding:36px}.contact-kind{border:0;padding:0;margin:0 0 28px;display:grid;grid-template-columns:1fr 1fr;gap:12px}.contact-kind legend{font-size:15px;margin-bottom:12px;font-weight:600}.contact-kind label{display:flex;gap:10px;padding:18px 14px;border:1px solid #d4dce6;border-radius:6px;cursor:pointer;align-items:flex-start}.contact-kind label:has(input:checked){border-color:#294ddd;background:#f4f6ff}.contact-kind input{margin-top:4px;accent-color:#294ddd}.contact-kind strong{display:block;font-size:15px;line-height:1.4}.contact-kind small{display:block;margin-top:6px;color:#566577;font-size:12px;line-height:1.5}.contact-fields{display:grid;grid-template-columns:1fr 1fr;gap:18px}.contact-field{display:flex;flex-direction:column;gap:8px;margin-bottom:22px;min-width:0}.contact-field label{font-size:14px;font-weight:600}.contact-field label span{font-weight:400;color:#68768a;font-size:11px}.contact-field input,.contact-field select,.contact-field textarea{font:inherit;font-size:16px;color:#162e50;width:100%;min-width:0;border:1px solid #cbd4df;background:#fcfcfd;border-radius:5px;padding:12px 14px;line-height:1.5}.contact-field textarea{resize:vertical;min-height:160px}.contact-field :is(input,textarea,select):focus{outline:2px solid #294ddd;outline-offset:2px}.contact-field small,.contact-field p{font-size:12px;line-height:1.55;color:#5a687c;margin:0}.contact-message>small{text-align:right;font-variant-numeric:tabular-nums}.contact-section-heading{border-top:1px solid #e3e7ed;padding-top:24px;margin-bottom:20px}.contact-section-heading h2{font-size:23px;margin:0 0 8px}.contact-section-heading p{font-size:13px;line-height:1.6;color:#5a687c}.contact-check{display:flex;gap:20px;align-items:center;padding:16px 20px;background:#f3f5f9;margin:4px 0 22px;border-radius:6px}.contact-check .contact-field{margin:0}.contact-check input{max-width:100px}.contact-check button,.contact-context button{padding:0;background:none;border:0;color:#294ddd;text-decoration:underline;text-underline-offset:4px;font:inherit;font-size:12px;cursor:pointer}.contact-consent{display:flex;gap:10px;align-items:flex-start;font-size:12px;line-height:1.65;color:#526177}.contact-consent input{margin-top:4px;accent-color:#294ddd;min-width:16px;min-height:16px}.contact-consent a{color:#294ddd;text-decoration:underline}.contact-submit{width:100%;justify-content:center;margin-top:12px}.contact-submit:disabled{opacity:.55;cursor:wait}.contact-fine{text-align:center;font-size:12px;color:#617085;line-height:1.6;margin:14px 0 0}.contact-status{font-size:14px;line-height:1.6;color:#853b23;margin-top:20px}.contact-status:empty{display:none}.contact-aside{padding-top:20px}.contact-aside-number{font-family:Georgia,serif;font-style:italic;font-size:112px;line-height:1;color:#bdc9dd;margin-bottom:26px}.contact-aside h2{font-size:29px;line-height:1.3;margin:0 0 20px}.contact-aside p{font-size:14px;line-height:1.85;color:#566577}.contact-aside-note{border-top:1px solid #d3dbe6;margin-top:30px;padding-top:26px}.contact-aside h3{font-size:17px;margin-bottom:12px}.contact-email{margin:30px 0}.contact-email span{display:block;font-size:12px;color:#68768a;margin-bottom:8px}.contact-email a{font-size:14px;color:#294ddd;overflow-wrap:anywhere}.contact-aside details{border-top:1px solid #d3dbe6;padding-top:20px}.contact-aside summary{font-size:13px;cursor:pointer}.contact-aside details p{font-size:12px}.contact-context{padding:16px;background:#f3f5f9;margin-bottom:24px;border-radius:6px;font-size:12px}.contact-context span{display:block;color:#68768a;margin-bottom:8px}.contact-context a{color:#294ddd;margin-right:15px}.contact-trap{position:absolute;left:-10000px;width:1px;height:1px;overflow:hidden}.contact-success{padding:40px 0}.contact-success h2{font-size:36px;line-height:1.2;margin:20px 0}.contact-success p{line-height:1.8;color:#566577}.contact-success .text-link{display:block;margin-top:24px}.contact-success [id]{font-size:12px}.contact-card [hidden],.contact-context[hidden]{display:none!important}@media(max-width:900px){.contact-layout{gap:32px;grid-template-columns:minmax(0,1.5fr) minmax(220px,1fr)}.contact-card{padding:24px}.contact-kind{grid-template-columns:1fr}}@media(max-width:680px){.contact-layout{grid-template-columns:1fr;gap:28px}.contact-card{padding:22px 18px}.contact-fields{grid-template-columns:1fr;gap:0}.contact-aside-number{display:none}.contact-check{padding:14px;gap:16px}.contact-kind label{padding:15px}.contact-aside{padding:6px 6px 30px}}
.archive-live .eyebrow{margin-bottom:18px}.archive-live>p{font-size:14px;line-height:1.7}.archive-live label{display:block;font-size:14px;margin:18px 0 10px}.archive-live input[type=range]{width:100%;accent-color:#294ddd;min-height:32px}.archive-live output{font-weight:600}.archive-live [role=status]{min-height:4em}.archive-cycle{display:flex;align-items:center;justify-content:center;gap:10px;margin:24px 0}.archive-cycle span{display:grid;place-items:center;width:52px;aspect-ratio:1;background:#fff;border:1px solid #cbd4e0;border-radius:50%;font-size:25px;color:#617085}.archive-cycle .is-active{background:#294ddd;border-color:#294ddd;color:#fff}.archive-cycle b{font-weight:400;color:#8c9bb0}.archive-ask{display:flex;flex-wrap:wrap;gap:12px 25px}.archive-ask p{width:100%;margin:0}@media(max-width:450px){.archive-cycle{gap:7px}.archive-cycle span{width:40px;font-size:22px}}
/* An explicit, optional page attachment in the contact form. */
section.contact-context{display:block;background:#f4f6fa;padding:20px;border:1px solid #e0e6ef;border-radius:8px;margin:0 0 28px;min-width:0}section.contact-context h2{font-size:15px;line-height:1.5;margin:0 0 10px;font-weight:600}section.contact-context h2 span{font-size:11px;font-weight:400;color:#68768a;display:block}section.contact-context p{font-size:13px;line-height:1.65;color:#566577;margin:8px 0 12px}section.contact-context #contact-context-link{display:block;font-size:16px;font-weight:600;line-height:1.55;overflow-wrap:anywhere;margin:12px 0;color:#294ddd}section.contact-context .contact-context-actions{display:flex;flex-wrap:wrap;gap:8px 20px;margin-top:12px}section.contact-context button{min-height:36px;font-size:13px;text-align:left}section.contact-context button:disabled{opacity:.5;cursor:default}section.contact-context #contact-context-editor{border-top:1px solid #d5ddeb;margin-top:16px;padding-top:18px}section.contact-context .contact-field{margin-bottom:0}section.contact-context #contact-context-error{color:#853b23}section.contact-context #contact-context-status:empty,section.contact-context #contact-context-error:empty{display:none}section.contact-context #contact-context-apply{background:#294ddd;color:white;border-radius:5px;padding:8px 16px;text-decoration:none}section.contact-context [hidden]{display:none!important}

/* UX release 2026-10-07: a single playable entry and compact lesson endings. */
.ux-home{max-width:1100px}.home-opening{padding:36px 0 20px;max-width:850px}.home-opening h1{font-size:clamp(32px,5vw,64px);line-height:1.05;margin:14px 0 18px;letter-spacing:-.035em}.home-opening>p:not(.eyebrow){font-size:18px;line-height:1.55;max-width:720px;margin:12px 0}.home-opening .eyebrow{font-size:11px;letter-spacing:.12em}
.frog-home{margin:10px 0 30px;padding:24px 32px}.frog-panel h2{font-size:26px;margin:0 0 10px}.frog-panel .frog-rules{font-size:16px;line-height:1.55;margin:0 0 14px;max-width:790px}.frog-panel .puzzle-toolbar{margin:0 0 6px}.frog-panel .puzzle-counter{margin-left:auto}.frog-panel .frog-board{height:160px;margin:0;min-width:calc(var(--stones,7)*44px)}.frog-panel .frog-token{width:calc(100% / var(--stones,7));min-width:44px;min-height:64px;max-width:90px;touch-action:manipulation}.frog-panel .frog-token svg{width:100%;height:auto;max-height:65px}.frog-panel .frog-stone{width:calc(100% / var(--stones,7) - 5px)}.frog-rail{overflow-x:auto;max-width:100%}.frog-panel .frog-rail{margin-top:-42px;padding-top:42px}.frog-panel .puzzle-feedback{font-size:16px;line-height:1.5;min-height:3em;margin:8px 0}.frog-panel button,.frog-panel summary{min-height:44px}.frog-panel .puzzle-actions{gap:8px;margin:8px 0}.frog-panel .puzzle-actions button{padding:10px 14px;font-size:15px}.frog-panel .puzzle-fine{font-size:13px;margin:12px 0}.frog-panel .frog-why{margin:12px 0 0}.frog-panel .frog-why summary{font-size:17px;padding:12px 0}.frog-panel .frog-why .prose{font-size:17px}.frog-level-picker summary{cursor:pointer;line-height:44px}.frog-static{display:block;text-align:center;font-size:24px;padding:50px 0}
.home-directions{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:28px;padding:30px 0;border-bottom:1px solid var(--line)}.home-directions h2{font-size:23px;line-height:1.25;margin-bottom:15px}.home-directions a{display:block;padding:8px 0;min-height:44px}.ux-home .home-author{grid-template-columns:180px 1fr;gap:35px;padding:40px 0;margin:0}.home-author picture{display:block}.ux-home .home-author img{width:180px;height:auto;aspect-ratio:4/5;object-fit:cover}.ux-home .home-author h2{font-size:28px}.ux-home .home-author p{font-size:17px;max-width:650px}.about-author img{height:auto;aspect-ratio:4/5}.about-lesson-links picture{max-width:360px}.about-lesson-links picture img{width:100%;height:auto;aspect-ratio:2/3;object-fit:cover}
.site-footer{padding:26px 0 20px}.site-footer .footer-links{display:flex;flex-wrap:wrap;gap:4px 24px;max-width:none;align-items:center}.site-footer .footer-links a{display:inline-flex;align-items:center;min-height:44px;font-size:14px}.site-footer .footer-bottom{margin-top:15px;padding-top:15px;font-size:12px}.lesson-ending{margin-top:24px;border-top:1px solid #dce3eb;padding-top:18px}.lesson-ending .source-panel{padding:0 0 16px;margin:0}.lesson-ending .source-panel h2{font-size:17px;margin:0 0 8px}.lesson-ending .source-panel p{font-size:14px;line-height:1.6;margin:6px 0}.lesson-ending .archive-ask{padding:12px 0;margin:8px 0;border:0;font-size:15px}.lesson-ending .lesson-pager{margin:14px 0;padding:14px 0}.lesson-ending .practice-next,.lesson-ending .topic-lesson-links{width:100%;max-width:none;margin:0;padding:18px 0}.lesson-ending .practice-next h2{font-size:23px;line-height:1.3;margin:4px 0 15px}.practice-next-compact{font-size:16px}.lesson-ending .topic-lesson-links>p{font-size:14px}.lesson-ending .library-practice{margin:12px 0}.lesson-ending .task-progress-tools{margin:12px 0;padding:0}.lesson-ending .task-progress-tools button{min-height:44px}.topic-lesson-links summary{min-height:44px}
@media(max-width:700px){.home-opening{padding-top:22px}.home-directions{grid-template-columns:1fr;gap:15px}.home-directions h2{font-size:21px;margin:0 0 4px}.home-directions section{padding-bottom:12px}.ux-home .home-author{grid-template-columns:128px 1fr;gap:18px}.ux-home .home-author img{width:128px}.ux-home .home-author h2{font-size:23px}.ux-home .home-author p{font-size:16px}.ux-home .home-author .actions{display:block}.ux-home .home-author .actions a{display:block;padding:10px 0}}
@media(max-width:500px){.frog-panel{padding:16px 12px;margin-inline:-16px;width:calc(100% + 32px)}.frog-panel .frog-board{height:140px}.frog-panel .frog-token{min-height:58px}.frog-panel .frog-rules{font-size:15px}.frog-panel .puzzle-actions button{padding:10px}.frog-panel .puzzle-fine{font-size:12px}.frog-panel .frog-rail{margin-inline:-12px;margin-top:-42px;padding-top:42px;max-width:none;width:calc(100% + 24px)}.frog-panel .frog-token.hinted{outline-offset:-2px}.frog-panel .frog-token:focus-visible{outline:2px solid var(--navy);outline-offset:-2px;border-radius:4px}.frog-panel .frog-direction{font-size:13px}.frog-panel .puzzle-feedback{font-size:15px}.ux-home .home-author{grid-template-columns:1fr}.ux-home .home-author picture{width:128px}.site-footer .footer-links{gap:0 20px}.site-footer .footer-bottom{display:block}}

.frog-panel .puzzle-toolbar{display:flex;min-height:26px}.frog-panel .puzzle-counter{font-size:15px}.frog-panel .puzzle-counter strong{font-size:20px}.frog-panel .frog-direction{margin-top:8px}
@media(max-width:500px){.home-opening{padding:16px 0 12px}.home-opening h1{margin:10px 0 12px}.home-opening>p:not(.eyebrow){font-size:16px;line-height:1.5;margin:10px 0}.frog-home{margin-top:4px}.frog-home .frog-board{height:122px}.frog-home h2{font-size:24px}.frog-home .frog-rules{margin-bottom:8px}}

.frog-goal{font-size:17px;margin:8px 0 12px;line-height:1.4}@media(max-width:500px){.home-opening{padding:14px 0 10px}.home-opening h1{font-size:29px;line-height:1.12;margin:10px 0 12px}.home-opening>p:not(.eyebrow){font-size:16px;line-height:1.45;margin:10px 0}.ux-home .frog-panel{margin-top:10px}.ux-home .frog-panel h2{font-size:23px;margin:0 0 6px}.ux-home .frog-goal{font-size:16px;margin:6px 0 10px}.ux-home .frog-rules{margin:10px 0;line-height:1.45}}

/* Text enlargement must wrap, never force a wider page. */
.nav{flex-wrap:wrap;min-width:0}.nav>a{max-width:100%;white-space:normal;overflow-wrap:anywhere}.nav-wrap{min-width:0}.ux-home h1,.ux-home h2,.about-project h1,.about-project h2{overflow-wrap:anywhere}.about-project section>*,.ux-home .home-author>*{min-width:0}.frog-panel .puzzle-toolbar{flex-wrap:wrap}

.about-project .review-card,.about-project .review-card>*{min-width:0;max-width:100%;overflow-wrap:anywhere}@media(max-width:500px){.nav-wrap{gap:8px}}

.about-project .document-card,.about-project .document-card>*{min-width:0;max-width:100%;overflow-wrap:anywhere}@media(max-width:500px){.site-header .nav-wrap{gap:8px}.about-project .document-grid{grid-template-columns:minmax(0,1fr)}}

/* One chosen response channel; hidden fields never reserve space. */
.contact-card [hidden]{display:none!important}.contact-kind{flex-wrap:wrap}.contact-kind label{min-width:0}.contact-field select{min-height:44px}.contact-fields:has([data-contact-channel]){display:block}.contact-method-help{font-size:14px}