@font-face{font-family:Geist;src:url('../assets/fonts/geist.woff2') format('woff2');font-display:swap;font-weight:100 900}
@font-face{font-family:Instrument;src:url('../assets/fonts/instrument-serif.woff2') format('woff2');font-display:swap}
@font-face{font-family:Instrument;src:url('../assets/fonts/instrument-serif-italic.woff2') format('woff2');font-display:swap;font-style:italic}
:root{--bg:#f1ece0;--surface:#fbf7ee;--surface2:#efe8d8;--text:#18221c;--muted:#6b6e63;--border:#e0d7c2;--green:#0e2a20;--accent:#d4a24c;--accentText:#89621f;--link:#234d39;--rail:224px;color-scheme:light}
:root[data-theme=dark]{--bg:#0b1a14;--surface:#14271d;--surface2:#1c3326;--text:#f5ebd6;--muted:#b8ae93;--border:#2e4836;--accent:#e8c77a;--accentText:#e8c77a;--link:#d4dfc1;color-scheme:dark}
*{box-sizing:border-box}html{scroll-padding-top:100px}body{margin:0;background:var(--bg);color:var(--text);font-family:Geist,Arial,sans-serif;font-size:14px;line-height:1.6;-webkit-tap-highlight-color:transparent}a{color:inherit;text-decoration:none}button,input,select{font:inherit}button,a,input,select,summary{touch-action:manipulation}button{cursor:pointer;color:inherit}button:disabled{cursor:default}img{max-width:100%;height:auto}svg.icon{width:20px;height:20px;flex:none;fill:none;stroke:currentColor;stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round}h1,h2,h3,p{margin:0}h1,h2{font-family:Instrument,Georgia,serif;font-weight:400;line-height:1.12}h3{font-weight:600;font-size:16px;line-height:1.4}em{font-weight:400}a,button{outline-offset:5px}:focus-visible{outline:2px solid var(--accentText)}[hidden]{display:none!important}.muted{color:var(--muted)}.eyebrow{font-size:10px;letter-spacing:.14em;font-weight:600;color:var(--muted);line-height:1.5}.icon-button{display:inline-flex;align-items:center;justify-content:center;width:44px;height:44px;border:1px solid transparent;border-radius:50%;background:transparent;flex:none}.icon-button:hover{background:var(--surface2)}.button{display:inline-flex;align-items:center;justify-content:center;gap:12px;min-height:46px;padding:11px 20px;border-radius:8px;font-weight:600;font-size:13px;border:1px solid transparent;text-align:center}.primary{background:var(--green);color:#fbf7ee}.gold{background:var(--accent);color:#14271d}.outline{background:transparent;border-color:var(--border)}.completed{background:var(--surface2);color:var(--link);border-color:var(--link)}.button:hover{filter:brightness(.95)}.text-link{font-size:12px;font-weight:600;color:var(--link)}.text-link:hover{text-decoration:underline}.skip{position:fixed;top:-80px;left:20px;z-index:100;background:var(--surface);padding:10px}.skip:focus{top:10px}
.topbar{height:80px;position:sticky;top:0;z-index:20;display:flex;align-items:center;gap:24px;padding:0 28px;background:var(--surface);border-bottom:1px solid var(--border)}.brand{display:flex;align-items:center;gap:11px;min-width:210px;font-size:24px;font-family:Instrument,Georgia,serif;line-height:1}.brand .elite{color:var(--accentText)}.brand small{display:block;font:8px/1.8 Geist,sans-serif;letter-spacing:.13em;color:var(--muted);margin-top:6px}.brand img{flex:none}.topbar-center{margin-left:12px;color:var(--muted);font-size:11px;display:flex;align-items:center;gap:14px}.version{font-size:9px;letter-spacing:.1em;border:1px solid var(--border);border-radius:4px;padding:3px 7px;color:var(--accentText)}.header-actions{margin-left:auto;display:flex;align-items:center;gap:15px}.signup{border:1px solid var(--border);background:transparent;border-radius:7px;font-size:12px;padding:5px 14px;color:var(--muted)}.signup span{display:block;font-size:9px}#menu{display:none}.sidebar{width:var(--rail);position:fixed;left:0;top:80px;bottom:0;border-right:1px solid var(--border);padding:29px 15px 24px;background:var(--surface);overflow:auto;z-index:15}.sidebar-top{padding:0 12px 20px}.sidebar-top .eyebrow{font-size:8px;letter-spacing:.12em}.sidebar nav>a,.nav-disabled{display:flex;align-items:center;gap:12px;padding:10px 13px;border-radius:7px;font-size:12px;min-height:44px;margin-bottom:2px}.sidebar nav>a[aria-current]{background:var(--green);color:#f1ece0}.sidebar nav>a:hover:not([aria-current]){background:var(--surface2)}.sidebar .icon{width:17px;height:17px}.nav-label{font-size:9px;color:var(--muted);letter-spacing:.12em;padding:24px 13px 8px}.nav-disabled{color:var(--muted);opacity:.77}.nav-disabled small{display:block;font-size:8px;line-height:1.2;color:var(--muted)}.sidebar-note{margin:34px 13px 0;padding-top:20px;border-top:1px solid var(--border);font-family:Instrument,serif;font-style:italic;font-size:19px}.sidebar-note small{display:block;font:11px/1.8 Geist,sans-serif;color:var(--muted);margin-top:4px}.sidebar-note div{font:9px Geist,sans-serif;color:var(--muted);margin-top:20px}.main-shell{margin-left:var(--rail);min-width:0}main{max-width:1300px;margin:auto;padding:32px 38px 60px;min-height:calc(100vh - 190px)}main:focus{outline:none}footer{margin:0 38px;max-width:1224px;border-top:1px solid var(--border);display:flex;gap:18px;justify-content:space-between;padding:22px 0 30px;font-size:10px;color:var(--muted)}footer>span:first-child{font-family:Instrument,serif;font-size:17px;color:var(--text)}footer a{padding:3px}.bottom-nav{display:none}.banner{padding:10px 24px;background:var(--surface2);font-size:12px;border-bottom:1px solid var(--border)}.toast{position:fixed;bottom:26px;left:50%;transform:translateX(-50%);background:var(--green);color:#fbf7ee;border:1px solid #56764b;padding:12px 22px;border-radius:9px;box-shadow:0 8px 30px #0002;z-index:80;max-width:90vw;width:max-content;font-size:12px}.scrim{position:fixed;inset:80px 0 0;background:#00100870;border:0;z-index:25}
.hero{background:linear-gradient(145deg,#0e2a20,#081912);color:#f4f1ea;border-radius:16px;display:grid;grid-template-columns:1.2fr 1fr;align-items:center;min-height:380px;padding:40px 40px 36px;overflow:hidden;position:relative}.hero:before{content:'';position:absolute;inset:0;pointer-events:none;background-image:radial-gradient(#d4a24c22 .7px,transparent .7px);background-size:20px 20px;opacity:.35}.hero-copy,.hero-art{position:relative}.hero-badge{display:inline-flex;align-items:center;gap:7px;font-size:8px;letter-spacing:.12em;color:#e4bd79;border:1px solid #d4a24c40;border-radius:20px;background:#d4a24c10;padding:5px 10px;margin-bottom:24px}.hero-badge i{width:5px;height:5px;background:#d4a24c;border-radius:50%}.hero h1{font-size:clamp(42px,4.7vw,65px);line-height:.99;letter-spacing:-.02em}.hero h1 em{color:#d4a24c}.hero-subtitle{font-family:Instrument,serif;font-style:italic;color:#dacfb3;font-size:21px;margin-top:14px}.hero-description{font-size:12px;line-height:1.8;color:#d3d9cd;max-width:375px;margin-top:18px}.hero-actions{display:flex;align-items:center;gap:24px;margin-top:24px}.hero-link{display:flex;align-items:center;gap:8px;font-size:11px;color:#f1ece0}.hero-link .icon{width:15px}.hero-footnote{margin-top:22px;color:#c2cbbd;display:flex;align-items:center;gap:10px;font-size:9px}.hero-footnote .icon{width:13px;height:13px;color:#d4a24c}.hero-art{text-align:center;align-self:center}.hero-art img{width:100%;max-width:430px;display:block;margin:auto}.art-caption{color:#d4a24c;font-size:8px;letter-spacing:.2em}.welcome-strip{border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;gap:24px;padding:18px 4px;font-size:10px;color:var(--muted)}.welcome-strip>span:first-child{display:flex;align-items:center;gap:8px;color:var(--link);flex:none}.welcome-strip .icon{width:14px;height:14px}.welcome-strip>span:last-child{min-width:0}.welcome-strip a{display:flex;gap:8px;align-items:center}.section{margin-top:36px}.section-heading{display:flex;align-items:end;justify-content:space-between;gap:24px;margin-bottom:19px}.section-heading .eyebrow{margin-bottom:7px;font-size:9px}.section-heading h2{font-size:31px}.section-heading h2 em{color:var(--accentText)}.class-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px}.class-card{border:1px solid var(--border);border-radius:10px;background:var(--surface);padding:18px 12px;display:flex;align-items:center;gap:12px;min-width:0}.class-card>div{min-width:0}.class-symbol{width:42px;height:48px;border-radius:7px;display:flex;align-items:center;justify-content:center;font:30px Instrument,serif;flex:none}.blue{color:#326697;background:#3b82c414}.purple{color:#7750ad;background:#7c5bc414}.green{color:#527741;background:#5b8f4e14}.rose{color:#a05242;background:#a8362c12}.gold.class-symbol{color:#946621;background:#d4a24c19}[data-theme=dark] .class-symbol{color:var(--accent)}.class-card h3{font-size:12px;white-space:nowrap}.class-card p{font-size:9px;color:var(--muted);line-height:1.4;margin-top:3px}.class-status{display:block;font-size:8px;margin-top:7px;color:var(--link);font-weight:500}.class-card>.icon{width:13px;margin-left:auto}.class-card:not(.disabled):hover{border-color:var(--link);background:var(--surface2)}.disabled{color:var(--muted)}.disabled .class-symbol{opacity:.65}.soon{font-size:9px;letter-spacing:.01em;color:var(--muted);font-family:Geist,sans-serif;font-weight:400}.method-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.method-grid article{padding:24px 23px;border-left:1px solid var(--border);position:relative}.method-grid article:first-child{border-left:0}.method-number{font:14px Instrument,serif;color:var(--muted);position:absolute;right:20px;top:20px}.method-grid .icon,.method-play{height:25px;width:25px;color:var(--accentText);display:block;font-size:29px;line-height:25px}.method-grid h3{margin-top:16px;font-size:14px}.method-grid p{margin-top:7px;color:var(--muted);font-size:11px;line-height:1.8}.future-band{display:flex;align-items:center;justify-content:space-between;gap:28px;padding:28px 30px;border:1px solid var(--border);background:var(--surface);border-radius:12px;margin-top:36px}.future-band h2{font-size:30px;margin-top:7px}.future-band p:not(.eyebrow){font-size:11px;color:var(--muted);margin-top:10px;max-width:450px}.future-tags{display:flex;gap:8px;flex-wrap:wrap;max-width:210px}.future-tags>span{font-size:10px;border:1px solid var(--border);padding:7px 10px;border-radius:5px;min-width:90px}.future-tags .soon{display:block;font-size:8px}
.page-heading{margin:10px 0 28px}.page-heading h1{font-size:clamp(36px,4vw,49px);margin-top:10px;letter-spacing:-.02em}.page-heading h1 em{color:var(--accentText)}.page-heading>p:last-child:not(.eyebrow){color:var(--muted);font-size:13px;max-width:680px;margin-top:13px;line-height:1.8}.back{font-size:11px;color:var(--muted);display:inline-block;min-height:40px;padding-top:6px}.back:hover{color:var(--link)}.all-classes{grid-template-columns:repeat(3,minmax(0,1fr))}.all-classes .class-card{padding:24px 18px}.all-classes .class-card h3{font-size:15px}.all-classes .class-card p{font-size:11px}.all-classes .class-status{font-size:10px}.class-tabs{display:flex;gap:20px;overflow:auto;border-bottom:1px solid var(--border);padding:0 0 1px;scrollbar-width:thin;margin-bottom:26px;align-items:stretch}.class-tabs>a,.class-tabs>span{flex:none;min-height:46px;padding:10px 0;font-size:12px;display:flex;align-items:center;gap:6px;border-bottom:2px solid transparent}.class-tabs>a[aria-current]{color:var(--link);border-color:var(--accentText);font-weight:600}.class-tabs>span{font-size:11px;color:var(--muted)}.class-tabs small{font-size:8px;border:1px solid var(--border);padding:1px 4px;border-radius:3px}.class-summary{display:flex;gap:20px;align-items:center;margin:30px 0;padding:22px;background:var(--surface2);border-radius:10px}.class-summary>div{flex:1;max-width:450px}.class-summary strong{font-size:14px}.class-summary p{font-size:11px;color:var(--muted);margin:3px 0 7px}.class-summary>a{margin-left:auto}progress{display:block;width:100%;height:4px;appearance:none;border:0;border-radius:5px;overflow:hidden;background:var(--border);accent-color:var(--accentText)}progress::-webkit-progress-bar{background:var(--border)}progress::-webkit-progress-value{background:var(--accentText)}progress::-moz-progress-bar{background:var(--accentText)}.section-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.section-card{background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:25px;display:flex;flex-direction:column}.section-card>.icon{color:var(--accentText);margin-bottom:19px;width:26px;height:26px}.section-card h2{font-size:27px}.section-card p{font-size:12px;color:var(--muted);line-height:1.7;margin-top:9px;flex:1}.section-bottom{margin-top:24px;display:flex;justify-content:space-between;align-items:center;font-size:10px;padding-top:14px;border-top:1px solid var(--border)}.section-card:not(.disabled):hover{border-color:var(--link)}.section-card.disabled{background:transparent}.section-card.disabled>.icon{color:var(--muted)}.filter-row{display:flex;gap:18px;margin:25px 0}.search{display:flex;align-items:center;gap:12px;border:1px solid var(--border);background:var(--surface);padding:0 14px;border-radius:8px;flex:1;min-width:0;color:var(--muted)}.search input{width:100%;min-width:0;border:0;background:transparent;color:var(--text);padding:14px 0;font-size:13px}.search input:focus{outline:none}.search:focus-within{outline:2px solid var(--accentText)}.class-select{display:flex;align-items:center;gap:9px;font-size:11px}.class-select select{border:1px solid var(--border);background:var(--surface);border-radius:8px;padding:12px;color:var(--text)}.results-line{display:flex;justify-content:space-between;gap:15px;font-size:11px;color:var(--muted);margin:22px 0 16px}.chapter-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.chapter-card{border:1px solid var(--border);border-radius:10px;background:var(--surface);padding:12px 22px 20px}.chapter-top{display:flex;align-items:center;justify-content:space-between}.chapter-number{font:19px Instrument,serif;color:var(--accentText)}.pin{color:var(--muted)}.pin.selected{color:var(--accentText);background:var(--surface2)}.pin.selected svg{fill:#d4a24c33}.chapter-card>a{display:flex;flex-direction:column;min-height:126px;padding-top:12px}.chapter-card h2{font-size:25px;text-transform:none;line-height:1.1;flex:1}.chapter-card p{font-size:10px;color:var(--muted);margin:12px 0}.chapter-bottom{display:flex;align-items:center;gap:25px;margin-top:7px}.chapter-bottom .icon{width:16px;height:16px}.chapter-card:has(a:hover){border-color:var(--link)}.chapter-actions{display:flex;gap:10px;margin-bottom:20px}.resource-list{border-top:1px solid var(--border)}.resource-row{display:flex;align-items:center;gap:16px;padding:18px 12px;border-bottom:1px solid var(--border);background:var(--surface)}.resource-symbol{width:45px;height:45px;display:flex;align-items:center;justify-content:center;background:var(--surface2);border-radius:8px;color:var(--accentText);font:27px Instrument,serif;flex:none}.resource-copy{flex:1;min-width:0;padding:5px 0}.resource-copy:hover h3{text-decoration:underline;text-underline-offset:3px}.resource-meta{font-size:10px;color:var(--muted)}.resource-copy h3{font-size:14px;margin-top:4px;overflow-wrap:anywhere}.notice{font-size:12px;line-height:1.8;color:var(--muted);background:var(--surface2);border-radius:8px;padding:16px 20px;margin-top:22px}.empty{text-align:center;max-width:620px;margin:50px auto;padding:30px 20px}.empty-symbol{font:60px Instrument,serif;color:var(--accentText)}.empty h2{font-size:32px;margin:12px 0}.empty p{font-size:13px;color:var(--muted);margin:0 auto 25px;max-width:390px}.loading{padding:70px 20px;text-align:center;color:var(--muted)}
.reader-toolbar{display:flex;align-items:center;justify-content:space-between;gap:15px;border-top:1px solid var(--border);border-bottom:1px solid var(--border);padding:12px 0;margin-bottom:25px;font-size:11px;color:var(--muted)}.reader-toolbar>div{display:flex;gap:10px}.reader-layout{display:grid;grid-template-columns:minmax(0,1.65fr) minmax(270px,1fr);gap:24px;align-items:start}.sheet{min-width:0;background:var(--surface);padding:30px;border:1px solid var(--border);border-radius:12px}.sheet-heading{display:flex;justify-content:space-between;gap:15px;color:var(--muted);font-size:9px;margin-bottom:20px}.sheet h2{font-size:32px;margin-bottom:20px}.math-content{font-size:15px;line-height:1.85;overflow-wrap:break-word;min-width:0}.math-content p{margin:15px 0}.math-content h3{margin:28px 0 14px;font-size:16px}.math-content h3:first-child{margin-top:12px}.math-content figure{margin:20px 0}.math-content img{max-height:430px;object-fit:contain}.math-content figcaption{font-size:12px;color:var(--muted)}.math-display,.katex-display{overflow-x:auto;overflow-y:hidden;max-width:100%;padding:4px 0}.math-display .katex-display{margin:10px 0}.answer{background:var(--surface2);border-left:2px solid var(--accent);padding:5px 12px;margin:18px 0}.table-scroll{overflow:auto}.table-scroll table{min-width:300px;width:100%;border-collapse:collapse}.table-scroll td,.table-scroll th{padding:10px;border:1px solid var(--border);text-align:center}.hint{background:var(--surface2);border-radius:8px;padding:14px 18px;margin-top:28px}.hint summary{font-size:12px;font-weight:600;cursor:pointer;min-height:24px}.correction{border-top:1px solid var(--border);margin-top:30px;padding-top:18px}.correction>summary{display:flex;justify-content:space-between;list-style:none;cursor:pointer;min-height:44px;align-items:center;color:var(--link);font-weight:600;font-size:13px}.correction>summary::-webkit-details-marker{display:none}.correction[open]>summary>span:last-child{transform:rotate(45deg)}.correction .math-content{padding-top:10px}.reader-aside{position:sticky;top:103px;min-width:0}.video-panel{border:1px solid var(--border);padding:20px;border-radius:12px;background:var(--surface)}.video-panel h2{font-size:28px;margin:9px 0 20px}.video-stage{aspect-ratio:16/9;min-height:200px;background:#0a1f18;border-radius:8px;overflow:hidden;display:flex}.video-stage iframe{width:100%;height:100%;min-height:200px;border:0}.video-launch{background:radial-gradient(ellipse at 60% 30%,#234a35,#0a1f18);color:#f1ece0;border:0;width:100%;padding:22px 10px;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:12px}.play-circle{width:48px;height:48px;border:1px solid #d4a24c80;border-radius:50%;display:grid;place-items:center;color:#d4a24c;font-size:17px;padding-left:3px}.video-launch strong{font-size:12px}.video-launch>span:last-child{font-size:10px;color:#c5cdbf}.video-caption{display:flex;flex-wrap:wrap;justify-content:space-between;gap:9px;font-size:10px;color:var(--muted);margin-top:12px}.video-caption a{color:var(--link);text-decoration:underline}.video-error{font-size:12px;color:var(--muted);margin-top:12px}.study-note{padding:30px;background:var(--surface2);border:1px solid var(--border);border-radius:12px}.study-symbol{font:40px Instrument,serif;color:var(--accentText)}.study-note h2{font-size:30px;margin:8px 0 15px}.study-note p{font-size:12px;color:var(--muted);line-height:1.9}.study-note small{display:block;border-top:1px solid var(--border);margin-top:20px;padding-top:15px;font-size:10px;color:var(--muted)}.aside-progress{padding:22px 8px}.aside-progress h3{font-size:13px}.aside-progress p{color:var(--muted);font-size:11px;margin:8px 0 14px}.reader-end{margin-top:32px;padding-top:24px;border-top:1px solid var(--border)}.reader-end p{font-family:Instrument,serif;font-size:22px;margin-bottom:18px}.stats{display:grid;grid-template-columns:repeat(3,1fr);background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:24px;margin:30px 0}.stats article{border-right:1px solid var(--border);padding:0 20px}.stats article:last-child{border:0}.stats strong{font:52px Instrument,serif}.stats strong small{font-size:25px}.stats span{display:block;color:var(--muted);font-size:11px}.resume-card{display:flex;gap:25px;align-items:center;justify-content:space-between;padding:24px;background:var(--surface2);border-radius:10px;margin:24px 0}.resume-card h2{font-size:28px;margin-top:7px}.resume-card .button{flex:none}.progress-classes{display:grid;grid-template-columns:1fr 1fr;gap:20px}.progress-class{display:flex;gap:18px;align-items:center;background:var(--surface);border:1px solid var(--border);border-radius:10px;padding:22px}.progress-class>div{flex:1}.progress-class h3{font-size:14px}.progress-class p{font-size:11px;color:var(--muted);margin:5px 0 10px}.privacy{max-width:780px}.privacy h2{margin:30px 0 15px}.privacy h2:first-child{margin-top:0}.privacy p{margin-bottom:18px;color:var(--muted);line-height:1.85}
@media(min-width:1550px){main{padding-top:42px}.hero{min-height:435px}.hero h1{font-size:70px}.class-card{padding:20px 17px}.class-card h3{font-size:14px}}
@media(max-width:1190px){:root{--rail:200px}main{padding:26px}.topbar{padding:0 20px}.brand{min-width:180px}.topbar-center{margin-left:0}.hero{padding:30px}.hero h1{font-size:49px}.hero-badge{font-size:7px}.hero-actions{gap:16px}.class-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.class-card{padding:18px}.class-card h3{font-size:14px}.class-card p{font-size:10px}.chapter-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.section-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.reader-layout{grid-template-columns:minmax(0,1fr)}.reader-aside{position:static;display:grid;grid-template-columns:1.3fr 1fr;gap:24px;grid-row:1}.study-note{padding:20px}.study-note small{margin-top:10px;padding-top:10px}.reader-layout:has(.study-note) .reader-aside{display:none}.reader-aside .video-stage{max-height:360px}.sheet{padding:26px}.class-tabs{gap:18px}.welcome-strip>span:last-child{max-width:55%;text-align:right}.future-band{padding:24px}.future-band h2{font-size:27px}}
@media(max-width:900px){.topbar-center{display:none}.hero{grid-template-columns:1fr .75fr;padding:30px 26px}.hero h1{font-size:43px}.hero-description{font-size:11px}.hero-subtitle{font-size:18px}.hero-art{margin-right:-30px}.hero-actions{flex-wrap:wrap;gap:14px}.hero-footnote{font-size:8px;gap:7px}.method-grid{gap:8px}.method-grid article{padding:18px 12px}.future-band{display:block}.future-tags{max-width:none;margin-top:20px}.section-heading h2{font-size:27px}.section-heading .text-link{font-size:10px}.progress-classes{grid-template-columns:1fr}.class-summary>a{display:none}.resource-row{gap:10px;padding:14px 8px}.resource-row>.icon-button:last-child{display:none}footer>span:nth-child(2){display:none}}
@media(max-width:700px){:root{--rail:0px}.topbar{height:70px;padding:env(safe-area-inset-top) max(16px,env(safe-area-inset-right)) 0 max(16px,env(safe-area-inset-left));min-height:calc(70px + env(safe-area-inset-top));gap:10px}.brand{font-size:23px;min-width:0;gap:8px}.brand img{width:37px;height:37px}.brand small{font-size:6.5px;margin-top:5px}.header-actions{gap:2px}.header-actions .icon-button{width:38px;height:42px}.signup{font-size:9px;padding:4px 7px;margin:0 3px}.signup span{font-size:7px}#menu{display:inline-flex;font-size:19px}.sidebar{top:calc(70px + env(safe-area-inset-top));bottom:0;width:270px;transform:translateX(-100%);z-index:30;padding-bottom:100px;visibility:hidden}.sidebar.open{transform:translateX(0);visibility:visible}.scrim{top:calc(70px + env(safe-area-inset-top))}.main-shell{margin-left:0}main{padding:20px max(16px,env(safe-area-inset-right)) 34px max(16px,env(safe-area-inset-left));min-height:calc(100vh - 195px)}.bottom-nav{position:fixed;bottom:0;left:0;right:0;display:flex;justify-content:space-around;gap:10px;z-index:20;border-top:1px solid var(--border);background:var(--surface);padding:8px max(10px,env(safe-area-inset-right)) calc(7px + env(safe-area-inset-bottom)) max(10px,env(safe-area-inset-left))}.bottom-nav a{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:4px;min-height:43px;flex:1;font-size:9px;color:var(--muted)}.bottom-nav a[aria-current]{color:var(--link);font-weight:600}.bottom-nav a[aria-current] .icon{background:var(--surface2);border-radius:5px;box-shadow:0 0 0 5px var(--surface2)}.bottom-nav .icon{width:20px;height:20px;margin-bottom:3px}footer{padding:16px 0 calc(95px + env(safe-area-inset-bottom));margin:0 18px;font-size:9px}.toast{bottom:calc(83px + env(safe-area-inset-bottom));font-size:11px;padding:12px 15px}.hero{grid-template-columns:1fr;min-height:0;padding:28px 24px 24px;border-radius:12px}.hero-badge{font-size:7px;margin-bottom:21px}.hero h1{font-size:49px;line-height:1.01}.hero-subtitle{font-size:20px;margin-top:13px}.hero-description{max-width:330px;font-size:12px;margin-top:14px}.hero-actions{gap:20px;margin-top:22px}.hero .button{font-size:12px;min-height:44px;padding:10px 16px}.hero-link{font-size:11px}.hero-footnote{font-size:9px;gap:9px;margin-top:19px}.hero-art{display:none}.welcome-strip{display:block;padding:15px 2px}.welcome-strip>span:first-child{font-size:10px}.welcome-strip>span:last-child{display:block;max-width:none;text-align:left;font-size:9px;margin-top:5px;margin-left:22px}.welcome-strip a{overflow:hidden;white-space:nowrap;text-overflow:ellipsis;display:block}.welcome-strip a svg{vertical-align:middle}.section{margin-top:28px}.section-heading{gap:15px;align-items:start;margin-bottom:16px}.section-heading h2{font-size:29px;line-height:1.1}.section-heading .eyebrow{font-size:8px}.section-heading .text-link{font-size:9px;text-align:right;flex:0 0 62px;margin-top:5px}.class-grid{gap:10px}.class-card{padding:15px 12px;gap:9px;border-radius:9px}.class-symbol{width:33px;height:42px;font-size:27px}.class-card h3{font-size:12px}.class-card p{font-size:9px}.class-card>.icon{display:none}.class-status,.class-status .soon{font-size:8px;margin-top:5px}.method-grid{grid-template-columns:1fr;gap:0}.method-grid article{display:grid;grid-template-columns:28px 1fr;column-gap:16px;border-left:0;border-top:1px solid var(--border);padding:21px 0}.method-grid article:first-child{border-top:0}.method-grid h3{grid-column:2;grid-row:1;margin:0;font-size:14px}.method-grid p{grid-column:2;margin-top:6px;font-size:11px;max-width:340px}.method-number{display:none}.method-grid .icon,.method-play{grid-column:1;grid-row:1;margin-top:0}.future-band{padding:22px;margin-top:23px}.future-band h2{font-size:30px}.future-band .eyebrow{font-size:8px}.future-tags{gap:7px}.future-tags>span{min-width:0;font-size:9px;flex:1;padding:7px}.future-tags .soon{font-size:7px}.page-heading{margin:5px 0 23px}.page-heading h1{font-size:39px;overflow-wrap:anywhere}.page-heading>p:last-child:not(.eyebrow){font-size:12px;margin-top:12px}.page-heading .eyebrow{font-size:9px}.all-classes .class-card{padding:18px 12px}.all-classes .class-card h3{font-size:12px}.all-classes .class-card p{font-size:9px}.all-classes .class-status{font-size:8px}.class-tabs{margin:0 -16px 23px;padding:0 16px;gap:21px}.class-tabs>a,.class-tabs>span{font-size:11px;min-height:47px;flex-direction:column;gap:0;justify-content:center}.class-tabs>span{font-size:10px}.class-tabs small{border:0;font-size:7px}.class-summary{padding:20px;margin:22px 0;gap:14px}.class-summary strong{font-size:13px}.class-summary p{font-size:10px}.section-grid{gap:11px}.section-card{padding:19px 16px;border-radius:9px}.section-card>.icon{width:23px;height:23px;margin-bottom:15px}.section-card h2{font-size:27px}.section-card p{font-size:10px;margin-top:8px}.section-bottom{margin-top:18px;padding-top:12px;font-size:9px}.section-bottom .icon{width:15px}.section-bottom .soon{font-size:8px}.filter-row{gap:10px;margin:20px 0}.class-select>span{display:none}.class-select select{padding:12px 6px;font-size:11px;max-width:100px}.search{padding:0 10px;gap:8px}.search input{font-size:11px;padding:13px 0}.search .icon{width:15px}.results-line{font-size:10px;margin:19px 0 14px}.chapter-grid{gap:11px}.chapter-card{padding:8px 15px 16px}.chapter-card>a{min-height:128px;padding-top:8px}.chapter-card h2{font-size:25px}.chapter-card p{font-size:9px;margin:10px 0}.chapter-number{font-size:18px}.chapter-card .pin{width:36px;height:36px}.chapter-bottom{gap:12px}.chapter-actions{margin-bottom:18px}.chapter-actions .button{font-size:11px;padding:9px 12px}.resource-row{gap:11px;padding:16px 10px}.resource-symbol{width:34px;height:39px;font-size:24px}.resource-copy h3{font-size:12px;line-height:1.5}.resource-meta{font-size:8px}.resource-row .pin{width:36px;height:40px}.resource-row .pin .icon{width:18px}.notice{font-size:11px;padding:15px}.empty{padding:15px;margin:30px auto}.empty h2{font-size:31px}.empty p{font-size:12px}.reader-toolbar{gap:8px;margin-bottom:18px;padding:10px 0}.reader-toolbar>span{font-size:9px}.reader-toolbar>div{gap:1px}.reader-toolbar .button{font-size:10px;min-height:41px;padding:9px 11px;gap:6px}.reader-toolbar .button .icon{width:15px}.reader-toolbar .pin{width:37px}.reader-layout{gap:18px}.reader-aside{grid-template-columns:1fr;gap:0}.reader-aside .aside-progress{display:none}.video-panel{padding:18px}.video-panel h2{font-size:29px;margin-bottom:16px}.video-panel .eyebrow{font-size:8px}.video-stage{min-height:200px}.video-caption{font-size:9px}.sheet{padding:22px 18px;border-radius:10px}.sheet-heading{font-size:8px;gap:12px}.sheet-heading .eyebrow{font-size:8px}.sheet h2{font-size:30px}.math-content{font-size:14px;line-height:1.85}.math-content h3{font-size:14px}.katex{font-size:1.08em}.correction>summary{font-size:12px}.reader-end p{font-size:22px}.reader-end .button{width:100%;font-size:12px}.stats{padding:20px 8px;margin:25px 0}.stats article{padding:0 12px}.stats strong{font-size:43px}.stats span{font-size:9px;max-width:70px;line-height:1.6}.resume-card{display:block;padding:21px}.resume-card h2{font-size:27px}.resume-card .button{margin-top:18px;font-size:12px}.progress-classes{gap:12px}.progress-class{padding:18px;gap:15px}.progress-class h3{font-size:13px}.progress-class p{font-size:10px}.privacy h2{font-size:29px}.privacy p{font-size:13px}}
@media(max-width:370px){.signup{display:none}.hero{padding:25px 19px}.hero h1{font-size:43px}.hero-actions{gap:15px}.hero-footnote{font-size:8px}.class-card{padding:13px 9px;gap:7px}.class-symbol{width:28px}.class-card h3{font-size:11px}.class-card p{font-size:8px}.class-status .soon{font-size:7px}.chapter-card{padding:8px 12px 14px}.chapter-card h2{font-size:23px}.section-heading h2{font-size:26px}.section-card{padding:18px 13px}.section-card h2{font-size:24px}.page-heading h1{font-size:35px}}
.video-panel,.video-stage{min-width:0;max-width:100%}.video-stage>iframe{min-width:0;flex:1;width:100%}
@media(max-width:700px){.reader-aside{grid-template-columns:minmax(0,1fr)}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important;animation:none!important}}
@media(max-width:370px){.signup{display:block}.brand{font-size:20px;gap:6px}.brand img{width:29px;height:29px}.brand small{display:none}.header-actions .icon-button{width:33px}.signup{padding:4px 5px}}
.standalone-sheet{max-width:860px;margin-inline:auto}.exercise-video{border-top:1px solid var(--border);margin-top:30px;padding-top:24px}.exercise-video h2{margin-top:10px}.exercise-video .video-stage{max-height:460px}.exercise-pagination{display:flex;flex-wrap:wrap;justify-content:space-between;gap:12px}.source-credit{font-size:10px;line-height:1.8;color:var(--muted);margin-top:26px}.source-credit a{text-decoration:underline}.source-note{margin-top:24px;padding:12px 16px;border:1px solid var(--border);border-radius:8px;background:var(--surface2);font-size:12px;color:var(--muted)}.source-note summary{cursor:pointer;min-height:26px}.source-note .math-content{font-size:12px}@media(max-width:700px){.standalone-sheet{padding:22px 16px}.exercise-pagination .button{width:auto;flex:1;font-size:11px;padding:10px}.exercise-video .video-stage{min-height:200px}}
:root{--rail:0px}.main-shell{margin-left:0}footer{margin-inline:auto;max-width:1224px;padding-inline:20px}.topbar-center{display:none}.top-nav{display:flex;gap:10px;margin-left:auto;margin-right:auto}.top-nav a{display:flex;align-items:center;gap:8px;min-height:44px;padding:9px 17px;font-size:12px;border-radius:7px;color:var(--muted)}.top-nav a[aria-current]{color:var(--link);background:var(--surface2)}.top-nav .icon{width:17px;height:17px}.chapter-bottom>span{font-size:10px;color:var(--muted);flex:1}@media(max-width:700px){.top-nav{display:none}.header-actions{margin-left:auto}footer{margin:0 18px;padding-inline:0}}

/* Published correction types: separate badges when both formats are available. */
.correction-tags{display:inline-flex;flex-wrap:wrap;gap:6px;vertical-align:middle}.correction-tags:empty{display:none}.resource-copy>.correction-tags:not(:empty){margin-top:9px}.correction-tag{display:inline-flex;align-items:center;gap:5px;border:1px solid var(--border);border-radius:6px;padding:4px 7px;background:var(--surface2);color:var(--link);font-size:10px;font-weight:600;line-height:1.4;white-space:nowrap}.correction-tag .icon{width:14px;height:14px;flex:none}.correction-tag.video{color:var(--accentText)}
/* Readable equations on phones. A wide formula scrolls independently. */
.site-hidden{display:none!important}.math-content,.reader-layout,.reader-aside{min-width:0}.math-display{overflow:visible;max-width:100%}.katex-display{max-width:100%;overflow-x:auto;overflow-y:hidden;padding:10px 2px 12px;overscroll-behavior-x:contain;scrollbar-width:thin;scrollbar-color:var(--accent) transparent}.katex-display>.katex{display:block;width:max-content;min-width:100%;text-align:center}.math-content .inline-math{display:inline-block;max-width:100%;overflow-x:auto;overflow-y:hidden;vertical-align:middle;padding-block:3px;scrollbar-width:thin;overscroll-behavior-x:contain}.math-wide{border-bottom:1px dashed var(--accent)}.math-wide:focus-visible{outline:2px solid var(--accent);outline-offset:3px}.math-content .katex{overflow-wrap:normal;word-break:normal}.site-ad{margin:26px auto;text-align:center;width:100%;max-width:1100px;min-width:0}.site-ad small{display:block;color:var(--muted);font-size:10px;margin-bottom:6px;letter-spacing:.08em}.site-ad a{display:block}.site-ad img{width:auto;max-width:100%;max-height:280px;object-fit:contain;border-radius:8px;margin:auto}.site-ad-bottom{max-width:900px;margin-top:32px}.site-ad-bottom img{max-height:110px}.site-ad a:focus-visible{outline:2px solid var(--accent);outline-offset:4px}
@media(max-width:700px){.math-content{font-size:16px;line-height:1.85}.math-content h3{font-size:16px;line-height:1.6}.math-content .katex{font-size:1.08em}.sheet,.standalone-sheet{padding:20px 14px}.hint{padding:12px}.hint summary,.correction>summary{min-height:44px;display:flex;align-items:center;font-size:14px}.reader-layout{display:flex;flex-direction:column}.reader-layout>.sheet,.reader-aside{width:100%;min-width:0}.search input{font-size:16px}.site-ad-home img{max-height:180px}.site-ad-bottom img{max-height:85px}main{padding-bottom:calc(90px + env(safe-area-inset-bottom))}.math-content p{margin:18px 0}}

/* Long expressions stay within their own scrolling container. */
.math-content .math-display{overflow-x:auto;overflow-y:hidden}.math-content .katex-display{contain:paint}
.quiz-form fieldset{min-width:0;border:0;border-top:1px solid var(--border);margin:24px 0;padding:20px 0}.quiz-form legend{max-width:100%;font-weight:600;padding:0 0 12px}.quiz-choice{display:flex;align-items:flex-start;gap:12px;padding:12px;margin:8px 0;border:1px solid var(--border);border-radius:8px;cursor:pointer}.quiz-choice input{flex:none;margin-top:8px}.quiz-choice span{min-width:0}.quiz-choice:has(input:checked){background:var(--surface2);border-color:var(--link)}.quiz-feedback{padding:14px;border-radius:8px;background:var(--surface2);margin-top:12px}.quiz-feedback.correct{border-left:3px solid var(--link)}.quiz-feedback.incorrect{border-left:3px solid var(--accent)}.quiz-score{font-weight:600;margin-top:20px}.quiz-form .actions{display:flex;flex-wrap:wrap;gap:10px}

.video-stage video{width:100%;height:100%;object-fit:contain}.video-help{font-size:13px;line-height:1.6;overflow-wrap:anywhere}.video-help a{display:inline-block}