:root{--bg:#f6f4ef;--paper:#fffdfa;--sidebar:#eeece6;--text:#292c29;--soft:#535850;--muted:#777b72;--line:#ddded5;--accent:#a5323c;--accent-hover:#87232d;--tint:#f2e4e1;--green:#54735d;--green-tint:#e8ede5;--serif:Georgia,'Times New Roman',serif;--sans:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;color-scheme:light}
:root[data-theme=dark]{--bg:#1e211f;--paper:#262a27;--sidebar:#191d1a;--text:#e9e9df;--soft:#c3c8be;--muted:#a0aa9b;--line:#41473f;--accent:#e49796;--accent-hover:#f0b0ad;--tint:#412c2e;--green:#a4b99b;--green-tint:#2e3c2e;color-scheme:dark}
*{box-sizing:border-box}body{margin:0;font:14px/1.65 var(--sans);color:var(--text);background:var(--bg);-webkit-font-smoothing:antialiased}button,input,select,textarea{font:inherit}button,a,input,select{touch-action:manipulation}a{color:inherit;text-decoration:none}button{cursor:pointer}button:disabled{cursor:default;opacity:.55}button:focus-visible,a:focus-visible,summary:focus-visible,input:focus-visible,select:focus-visible,textarea:focus-visible{outline:3px solid 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i{width:5px;height:5px;background:var(--green);border-radius:50%}.icon-button{border:0;background:transparent;color:var(--muted);font-size:22px;width:32px;height:34px;display:grid;place-items:center}.mobile-brand,.mobile-nav{display:none}main{max-width:1320px;margin:auto;padding:34px 45px 56px;min-height:calc(100vh - 145px)}.page-topline{display:flex;align-items:center;justify-content:space-between;margin-bottom:36px}.page-topline .eyebrow{color:var(--muted);font-size:9px}.small-label{font-size:10px;color:var(--muted)}.hero{display:grid;grid-template-columns:1.25fr 1fr;align-items:center;gap:35px;min-height:285px}.hero h1{margin:14px 0 22px}.hero h1 em{color:var(--accent);font-weight:400}.hero-description{max-width:440px;color:var(--muted);font-size:13px;line-height:1.9}.hero-actions{display:flex;align-items:center;gap:24px;flex-wrap:wrap;margin-top:27px}.button{display:inline-flex;align-items:center;justify-content:center;gap:15px;padding:11px 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var(--line);padding:21px 0}.stat{padding-left:23px;border-left:1px solid var(--line)}.stat:first-child{padding-left:0;border:0}.stat strong{display:block;font:34px/1.2 var(--serif);margin-bottom:3px}.stat p{font-size:10px;color:var(--muted);margin:0}.stat span{font-size:9px;color:var(--muted)}.section-heading{display:flex;align-items:center;justify-content:space-between;gap:16px;margin:32px 0 20px}.section-heading h2{margin:0;font-size:29px}.section-heading .muted{font-size:10px}.topic-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.topic-card{padding:22px 21px 16px;background:var(--paper);border:1px solid var(--line);border-radius:7px;display:flex;flex-direction:column;min-height:218px;transition:transform .15s,border-color .15s}.topic-card:hover{transform:translateY(-3px);border-color:var(--accent)}.topic-card-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:24px}.topic-card-top 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var(--line);font-size:9px;color:var(--muted);gap:20px}.page-title{margin:8px 0 30px}.page-title h1{font-size:46px;margin:12px 0 16px}.page-title p{color:var(--muted);max-width:690px;font-size:13px;line-height:1.85}.back-link{display:inline-flex;gap:10px;color:var(--muted);font-size:11px;margin-bottom:25px}.article-layout{display:grid;grid-template-columns:minmax(0,1fr) 230px;gap:34px}.article-body{min-width:0}.article-section{margin-bottom:27px}.article-section h2{font-size:25px;margin-bottom:13px}.article-section p{font-size:14px;line-height:1.95;color:var(--muted);white-space:pre-line}.article-side{position:sticky;top:25px;align-self:start}.side-panel{padding:20px;background:var(--paper);border:1px solid var(--line);border-radius:7px;margin-bottom:14px}.side-panel h3{font-size:13px;margin-bottom:13px}.side-panel p,.side-panel a{font-size:11px;color:var(--muted)}.side-panel a{text-decoration:underline;text-underline-offset:4px}.side-panel .button{width:100%;text-decoration:none;color:var(--paper);margin-top:8px}.side-panel .button.secondary{color:var(--text)}.formula{font:20px/1.7 var(--serif);letter-spacing:.1px;overflow-wrap:anywhere;color:var(--accent);white-space:pre-line}.formula-card{padding:22px;border:1px solid var(--line);border-radius:7px;background:var(--paper)}.formula-card h3{font-size:12px;margin-bottom:13px}.formula-card p{font-size:11px;line-height:1.8;color:var(--muted);margin:11px 0 0}.formula-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}.formula-grid.article-formulas{grid-template-columns:1fr;margin:20px 0 26px}.trap{border-left:3px solid var(--accent);padding:14px 18px;background:var(--tint);font-size:12px;line-height:1.85;margin-bottom:11px;color:var(--muted)}.note-label{font-size:11px;color:var(--muted);display:block;margin-bottom:9px}textarea{width:100%;min-height:110px;resize:vertical;border:1px solid var(--line);border-radius:5px;background:var(--paper);padding:14px;color:var(--text)}.article-actions{display:flex;gap:12px;flex-wrap:wrap;margin:28px 0}.toolbar{display:flex;gap:12px;margin-bottom:23px;flex-wrap:wrap}.search,select{border:1px solid var(--line);border-radius:5px;color:var(--muted);padding:10px 13px;background:var(--paper);font-size:12px}.search{flex:1;min-width:190px}select{max-width:100%}.practice-tabs{display:flex;border-bottom:1px solid var(--line);gap:26px;margin-bottom:26px}.practice-tabs button{padding:0 0 13px;background:transparent;border:0;border-bottom:2px solid transparent;color:var(--muted);font-size:12px}.practice-tabs button.active{color:var(--accent);border-bottom-color:var(--accent)}.practice-layout{display:grid;grid-template-columns:minmax(0,1fr) 220px;gap:27px}.question-card{padding:30px;background:var(--paper);border:1px solid var(--line);border-radius:7px}.question-meta{display:flex;align-items:center;justify-content:space-between;font-size:10px;color:var(--muted);gap:15px;margin-bottom:22px}.question-card h2{font:27px/1.45 var(--serif);margin:0 0 24px;letter-spacing:-.3px}.options{display:grid;gap:10px}.option{display:flex;align-items:center;gap:13px;text-align:left;width:100%;padding:13px 15px;border:1px solid var(--line);background:transparent;color:var(--muted);border-radius:5px;font-size:13px;white-space:pre-line}.option:hover:not(:disabled){border-color:var(--accent);background:var(--tint)}.option-label{flex-shrink:0;font:11px ui-monospace,monospace;width:22px;height:22px;border:1px solid var(--line);border-radius:50%;display:grid;place-items:center}.option.correct{background:var(--green-tint);border-color:var(--green)}.option.incorrect{background:var(--tint);border-color:var(--accent)}.feedback{padding:17px 19px;background:var(--green-tint);border-left:3px solid var(--green);margin-top:22px;font-size:13px;color:var(--muted)}.feedback.wrong{background:var(--tint);border-color:var(--accent)}.feedback h3{margin:0 0 7px;font-size:13px}.feedback p{margin:0}.practice-controls{display:flex;gap:12px;margin-top:22px;align-items:center;flex-wrap:wrap}.practice-hint{padding:8px 0}.practice-hint h3{font:23px var(--serif);margin-bottom:12px}.practice-hint p{font-size:12px;color:var(--muted);line-height:1.85}.practice-stat{border-top:1px solid var(--line);padding-top:17px;margin-top:22px;font-size:12px}.practice-stat strong{font:30px var(--serif);color:var(--green);display:block}.numeric-row{display:flex;align-items:center;gap:12px;flex-wrap:wrap}.numeric-row input{min-width:0;width:210px;border:1px solid var(--line);border-radius:5px;background:var(--bg);padding:12px 14px;color:var(--text);font-size:18px}.steps{padding-left:20px;font-size:13px;line-height:1.9;color:var(--muted)}.steps li{padding-left:5px;margin-bottom:9px}.source-link{display:inline-block;font-size:10px;color:var(--muted);text-decoration:underline;text-underline-offset:3px;margin-top:14px}.empty-state{padding:40px 25px;text-align:center;border:1px solid var(--line);border-radius:7px;color:var(--muted)}.demo-grid{display:grid;grid-template-columns:1fr 1fr;gap:16px}.demo-card{padding:24px;border:1px solid var(--line);border-radius:7px;background:var(--paper)}.demo-card summary{cursor:pointer;list-style:none}.demo-card summary::-webkit-details-marker{display:none}.demo-card summary h2{font-size:27px;margin:16px 0 10px}.demo-card summary p{font-size:12px;color:var(--muted)}.demo-card summary .text-link{color:var(--accent);font-size:11px}.demo-card[open]{grid-column:1/-1}.demo-card[open] summary{border-bottom:1px solid var(--line);padding-bottom:20px;margin-bottom:22px}.demo-card .case-prompt{font-size:13px;white-space:pre-line;color:var(--muted);line-height:1.9;max-width:850px}.demo-step{max-width:850px;margin:24px 0}.demo-step h3{font-size:14px;margin-bottom:9px}.demo-step p{font-size:13px;white-space:pre-line;color:var(--muted);line-height:1.9}.answer-box{padding:20px;background:var(--green-tint);border:1px solid var(--line);border-radius:5px;white-space:pre-line;font-size:13px}.exam-setup{max-width:710px;padding:32px;border:1px solid var(--line);border-radius:8px;background:var(--paper)}.exam-setup h2{font-size:30px}.exam-setup p{color:var(--muted);font-size:13px;line-height:1.9}.exam-specs{display:flex;gap:30px;margin:27px 0}.exam-specs strong{font:33px var(--serif);display:block}.exam-specs span{font-size:11px;color:var(--muted)}.timer-bar{position:sticky;top:0;background:var(--paper);border:1px solid var(--line);padding:15px 21px;border-radius:6px;display:flex;align-items:center;gap:20px;margin-bottom:22px;z-index:10}.timer-bar strong{font:25px ui-monospace,monospace;color:var(--accent);margin-left:auto}.timer-bar span{font-size:12px;color:var(--muted)}.exam-tasks{display:grid;gap:18px}.exam-task{padding:25px;background:var(--paper);border:1px solid var(--line);border-radius:7px}.exam-task h2{font-size:26px;margin-bottom:15px}.exam-task>p{font-size:13px;white-space:pre-line;color:var(--muted);line-height:1.85}.exam-task input{display:block;margin-bottom:12px}.material-list{display:grid;grid-template-columns:1fr 1fr;gap:13px}.material-item{display:flex;align-items:center;gap:16px;padding:19px;border:1px solid var(--line);border-radius:6px;background:var(--paper)}.material-item:hover{border-color:var(--accent)}.pdf-icon{border:1px solid var(--line);color:var(--accent);padding:9px 6px;font-size:10px;font-weight:600;border-radius:3px}.material-item h3{font-size:12px;margin:0 0 5px}.material-item p{font-size:10px;color:var(--muted);margin:0}.material-item>span:last-child{margin-left:auto;color:var(--muted)}#toast{position:fixed;bottom:24px;left:calc(50% + 123px);transform:translateX(-50%) translateY(20px);background:var(--text);color:var(--bg);padding:11px 19px;font-size:12px;border-radius:5px;opacity:0;pointer-events:none;transition:.2s;z-index:100}#toast.show{opacity:1;transform:translateX(-50%) translateY(0)}.discreet-note{font-size:11px;color:var(--muted);line-height:1.8;margin:21px 0}.validation-error{color:var(--accent);font-size:12px;margin-top:9px}.route-banner{padding:16px 20px;background:var(--tint);border-left:3px solid var(--accent);font-size:12px;color:var(--muted);margin-bottom:25px}
@media(min-width:1500px){main{padding-top:45px}.hero{min-height:315px}.topic-card{min-height:234px}}@media(max-width:1150px){.sidebar{width:218px;padding:29px 18px}.workspace{margin-left:218px}.topbar{padding:0 30px}main{padding:30px}.hero{gap:16px}.hero h1{font-size:54px}.hero-art{max-width:315px}.topic-card{padding:18px;min-height:220px}.article-layout{grid-template-columns:minmax(0,1fr) 205px;gap:23px}.local-status{display:none}.practice-layout{grid-template-columns:minmax(0,1fr) 180px}#toast{left:calc(50% + 109px)}}
@media(max-width:950px){.hero{grid-template-columns:1.35fr 1fr}.hero h1{font-size:47px}.hero-description{font-size:12px}.hero-art{max-width:260px}.topic-grid{grid-template-columns:1fr 1fr}.article-layout{grid-template-columns:1fr}.article-side{position:static;display:grid;grid-template-columns:1fr 1fr;gap:14px}.formula-grid{grid-template-columns:1fr}.practice-layout{grid-template-columns:1fr}.practice-hint{display:flex;align-items:center;gap:20px;border-top:1px solid var(--line);padding-top:18px}.practice-hint>p{max-width:380px}.practice-stat{border:0;margin:0;padding:0}.study-note a{display:none}.demo-grid{grid-template-columns:1fr}.material-list{grid-template-columns:1fr}.hero-actions{gap:17px}.hero-actions .button{padding:10px 14px;font-size:11px}}
@media(max-width:700px){.sidebar{display:none}.workspace{margin-left:0}.topbar{height:64px;padding:0 22px}.breadcrumb{display:none}.mobile-brand{display:flex;align-items:center;gap:9px;font:italic 30px var(--serif);color:var(--accent)}.mobile-brand span{font:600 21px var(--sans);letter-spacing:-.7px;color:var(--text)}.mobile-nav{display:flex;position:sticky;top:0;z-index:25;background:var(--bg);border-bottom:1px solid var(--line);padding:11px 20px;gap:17px;overflow:auto}.mobile-nav a{font-size:11px;color:var(--muted);white-space:nowrap;padding:3px 0}.mobile-nav a.active{color:var(--accent)}main{padding:26px 22px 40px}.page-topline{margin-bottom:27px}.page-topline .small-label{font-size:8px}.hero{display:block;min-height:0}.hero h1{font-size:49px;letter-spacing:-1.6px;margin-top:10px}.hero-description{font-size:13px;max-width:420px}.hero-art{display:none}.hero-actions{margin-top:23px}.stats{margin:30px 0 27px;padding:18px 0}.stat{padding-left:12px}.stat strong{font-size:29px}.stat p{font-size:9px}.stat span{font-size:8px}.section-heading h2{font-size:27px}.section-heading .muted{font-size:9px}.topic-grid{gap:11px}.topic-card{padding:17px 15px;min-height:224px}.topic-card h3{font-size:14px}.topic-card p{font-size:11px}.topic-card-top{margin-bottom:20px}.topic-card-top .eyebrow{font-size:7px;letter-spacing:.8px}.topic-symbol{font-size:24px}.study-note{padding:20px 17px;gap:16px}.study-note h3{font-size:21px}.study-note p{font-size:11px}footer{padding:18px 22px;font-size:8px}footer span:first-child{max-width:220px}.page-title h1{font-size:38px}.page-title p{font-size:12px}.article-section p{font-size:13px}.article-section h2{font-size:25px}.article-side{grid-template-columns:1fr}.question-card{padding:23px 19px}.question-card h2{font-size:25px}.option{padding:12px 11px;font-size:12px;gap:10px}.feedback{padding:15px;font-size:12px}.practice-hint{display:block}.practice-stat{margin-top:16px}.practice-stat strong{display:inline;margin-right:12px}.demo-card{padding:22px 19px}.timer-bar{top:51px;padding:12px 15px;flex-wrap:wrap;gap:10px}.timer-bar .button{padding:7px 10px;font-size:10px;min-height:0}.timer-bar strong{font-size:22px}.timer-bar span{font-size:10px}.exam-task{padding:22px 19px}.exam-setup{padding:25px 21px}.formula{font-size:19px}#toast{left:50%;width:max-content;max-width:90%}.toolbar select{flex:1;min-width:0}.search{flex-basis:100%}.article-actions .button{flex:1}.numeric-row input{width:160px}.numeric-row .button{padding:11px}.exam-specs{gap:23px}}
@media(max-width:370px){.topic-grid{grid-template-columns:1fr}.hero h1{font-size:43px}.topic-card{min-height:190px}.stat strong{font-size:25px}.mobile-nav{gap:14px}.mobile-nav a{font-size:10px}}
@media(prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}@media print{.sidebar,.topbar,.mobile-nav,footer,.toolbar,.practice-tabs,.article-actions,.article-side,.back-link,.timer-bar,.button,#toast{display:none!important}.workspace{margin:0}main{padding:0;max-width:none}body{background:white;color:black}.article-layout{display:block}.demo-card{break-inside:avoid}.formula-card{break-inside:avoid}:root[data-theme]{--bg:white;--paper:white;--text:#222;--soft:#333;--muted:#555;--line:#ccc;--accent:#842731;--tint:#f5eeeb;--green-tint:#edf1e9;color-scheme:light}}
.icon-button-text{background:none;border:0;padding:9px 4px;color:var(--muted);cursor:pointer}.icon-button-text:hover{color:var(--accent)}

/* Each course keeps its own routes and local progress. */
.course-switch{display:grid;grid-template-columns:1fr 1fr;gap:10px;padding:16px 45px;border-bottom:1px solid var(--line);background:var(--bg)}
.course-tab{min-width:0;display:flex;align-items:center;gap:12px;padding:12px 17px;border:1px solid var(--line);border-radius:7px;color:var(--muted);transition:border-color .15s,background .15s}
.course-tab:hover{border-color:var(--accent);background:var(--paper)}.course-tab[aria-current=page]{background:var(--paper);border-color:var(--accent);color:var(--text)}
.course-tab strong{font-size:12px;font-weight:650;display:block}.course-tab small{display:block;font-size:10px;margin-top:2px;color:var(--muted)}.course-tab-arrow{margin-left:auto;font-size:17px;color:var(--muted)}
.course-dot{flex:0 0 9px;width:9px;height:9px;border-radius:50%;background:#a5323c}.black-course .course-dot{background:#2b3735;box-shadow:0 0 0 1px #ffffff50}.course-tab[aria-current=page] .course-tab-arrow{color:var(--accent)}
:root[data-course=black]{--accent:#2b4942;--accent-hover:#19372f;--tint:#e6ede7;--green:#527663;--green-tint:#e6eee6}
:root[data-course=black] .hero h1{font-size:clamp(40px,4vw,58px)}
:root[data-course=black][data-theme=dark]{--accent:#b5cebd;--accent-hover:#d2e7d7;--tint:#2e4037;--green:#b5cebd;--green-tint:#2e3c2e}
:root[data-theme=dark] .black-course .course-dot{background:#b5cebd}:root[data-theme=dark] .red-course .course-dot{background:#e49796}
.course-bridge{border:1px solid var(--line);border-radius:7px;background:var(--paper);padding:22px;margin:26px 0}.course-bridge h2{font-size:24px;margin:0 0 10px}.course-bridge p{font-size:12px;color:var(--muted);line-height:1.85;margin:0 0 14px}.bridge-links{display:flex;flex-wrap:wrap;gap:10px 18px}.bridge-links a{color:var(--accent);font-size:11px;text-decoration:underline;text-underline-offset:4px}
.course-map{display:grid;gap:14px}.course-map-row{display:grid;grid-template-columns:1fr 32px 1fr;align-items:stretch;gap:14px}.course-map-row>a{padding:22px;border:1px solid var(--line);border-radius:7px;background:var(--paper)}.course-map-row>a:hover{border-color:var(--accent)}.course-map-row h2{font-size:22px;margin:11px 0}.course-map-row p{font-size:12px;color:var(--muted);line-height:1.8;margin:0}.course-map-arrow{display:grid;place-items:center;color:var(--muted);font-size:22px}
.black-hero-art{padding:25px 12px 25px 25px}.valuation-sketch{position:relative;border-left:1px solid var(--line);border-bottom:1px solid var(--line);min-height:210px;display:flex;align-items:flex-end;justify-content:space-around;gap:17px;padding:26px 15px 0}.valuation-sketch>div{width:43px;background:var(--accent);position:relative;opacity:.8;border-radius:3px 3px 0 0}.valuation-sketch>div:last-child{background:var(--green);opacity:.48}.valuation-sketch span{position:absolute;bottom:-26px;left:0;width:100%;text-align:center;font:10px var(--sans);color:var(--muted)}.valuation-sketch b{position:absolute;top:-26px;left:0;width:100%;text-align:center;font:12px var(--serif);color:var(--accent)}.valuation-equation{font-size:15px;text-align:center;color:var(--accent);margin-bottom:27px}.black-hero-art>.art-note{position:static;display:block;margin-top:45px;font-size:10px;text-align:center}
.black-course-note{color:var(--muted);font-size:11px;line-height:1.8}.course-level-label{display:inline-flex;gap:7px;align-items:center;color:var(--green);font-size:10px;border:1px solid var(--line);border-radius:20px;padding:4px 10px}
@media(max-width:1150px){.course-switch{padding-inline:30px}}@media(max-width:700px){.course-switch{padding:12px 22px;gap:8px}.course-tab{padding:10px;gap:8px}.course-tab strong{font-size:11px}.course-tab small{font-size:9px}.course-tab-arrow{display:none}.course-dot{flex-basis:7px;width:7px;height:7px}.course-map-row{grid-template-columns:1fr;gap:0}.course-map-arrow{height:33px;transform:rotate(90deg)}.course-map-row>a{padding:19px}.course-bridge{padding:20px}.page-topline{gap:12px}.course-level-label{font-size:8px;white-space:nowrap}}
@media print{.course-switch,.course-bridge{display:none!important}}

/* Shared project navigation stays outside the course routes. */
.project-network{display:flex;align-items:center;justify-content:space-between;gap:14px;padding:0 46px;min-height:46px;border-bottom:1px solid var(--line);color:var(--muted);font-size:10px}.project-hub-link{display:inline-flex;align-items:center;gap:8px;min-height:44px;color:var(--accent);font-size:11px;font-weight:600;white-space:nowrap}.project-hub-link:hover{text-decoration:underline;text-underline-offset:4px}.project-network>span{font-size:10px}@media(max-width:1180px){.project-network{padding-inline:32px}}@media(max-width:700px){.project-network{padding-inline:22px}.project-network>span{display:none}}@media print{.project-network{display:none!important}}
/* Mathematics uses the same local KaTeX fonts on every route. */
.math-inline{display:inline;white-space:normal}.math-inline>.katex{font-size:1.06em;white-space:nowrap}.math-block{display:block;min-width:0;max-width:100%;overflow-x:auto;overflow-y:hidden;padding:14px 4px 17px;margin:12px 0;scrollbar-width:thin;scrollbar-color:var(--line) transparent;overscroll-behavior-x:contain;white-space:normal;line-height:1.6;overflow-wrap:normal}.math-block .katex-display{margin:0;text-align:center}.math-block .katex-display>.katex{white-space:nowrap;text-align:inherit}.math-block .katex{font-size:1.12em}.formula{font-family:var(--sans);font-size:16px;line-height:1.7;overflow-wrap:normal;letter-spacing:0}.formula>.math-block{margin:3px 0;padding:20px 2px}.formula .katex{font-size:1.23em}.formula-card{min-width:0;padding:23px 24px}.formula-card h3{font-size:12px;line-height:1.65}.formula-card h3 .muted{display:block;font-size:10px;font-weight:400;margin-top:4px}.formula-card p{line-height:1.9}.formula-card p .math-block{color:var(--muted);font-size:12px;padding-top:10px;padding-bottom:12px}.article-body,.demo-card,.demo-step,.feedback,.question-card,.exam-task{min-width:0}.steps .math-block{font-size:13px}.question-card h2 .katex{font-size:.9em}.article-section p,.demo-step p{line-height:2}.art-equation{position:absolute;top:20%;left:17%;color:var(--accent);font-size:18px}.answer-box .math-block{margin:0}.demo-step .math-block{background:var(--bg);border-radius:5px;padding:21px 12px}.question-card .feedback .math-block,.exam-task .feedback .math-block{background:transparent}.formula-grid{align-items:stretch}.formula-grid .formula-card{display:flex;flex-direction:column}.formula-grid .formula-card>.formula{flex:1;display:grid;align-content:center}.formula-grid .formula-card>p{margin-top:12px;padding-top:14px;border-top:1px solid var(--line)}
@media(max-width:700px){.formula-card{padding:20px 17px}.formula{font-size:15px}.formula .katex{font-size:1.12em}.math-block{max-width:100%;padding:15px 2px}.math-block .katex{font-size:1.05em}.demo-step .math-block{padding:20px 8px}.steps{padding-left:17px}.formula-card p .math-block{font-size:11px}}
@media print{.math-block{overflow:visible;break-inside:avoid}.formula-card,.demo-step{break-inside:avoid}}
.practice-tabs{overflow-x:auto;white-space:nowrap;gap:24px}.practice-tabs button{flex-shrink:0}.option .math-block{min-width:0;width:100%;padding:9px 0;margin:0;text-align:left;font-size:13px}.option .math-block .katex-display{text-align:left}.option .math-block .katex{font-size:1.09em}.option .option-label{align-self:center}.chosen-reason{border-top:1px solid var(--line);padding-top:13px;margin-top:13px!important}.chosen-reason strong{display:block;margin-bottom:5px}.practice-hint>.text-link{font-size:11px;color:var(--accent)}.term-count{display:flex;justify-content:space-between;gap:15px;font-size:11px;color:var(--muted);margin-bottom:18px}.term-grid{display:grid;grid-template-columns:1fr 1fr;gap:15px;align-items:start}.term-card{min-width:0;border:1px solid var(--line);border-radius:7px;background:var(--paper);padding:23px}.term-card summary{cursor:pointer;list-style:none}.term-card summary::-webkit-details-marker{display:none}.term-meta{display:flex;justify-content:space-between;align-items:center;margin-bottom:15px}.term-abbr{font:500 14px ui-monospace,monospace;color:var(--accent);background:var(--tint);padding:3px 8px;border-radius:4px}.term-plus{font-size:22px;color:var(--muted);line-height:1}.term-card[open] .term-plus{transform:rotate(45deg)}.term-card h2{font:500 18px/1.35 var(--sans);letter-spacing:-.3px;margin:0 0 12px}.term-card summary p{font-size:13px;line-height:1.85;color:var(--muted);margin:0}.term-details{border-top:1px solid var(--line);margin-top:19px;padding-top:20px}.term-example .eyebrow{font-size:8px;color:var(--muted)}.term-example p{font-size:12px;line-height:1.9;color:var(--muted);margin-top:8px}.term-details>.formula{font-size:14px}.term-details .trap{font-size:11px}.term-links{display:flex;flex-wrap:wrap;gap:8px 16px}.term-links a{color:var(--accent);font-size:10px}.term-links a:hover{text-decoration:underline}.practice-hint{display:block}.formula-card>.source-link{margin-top:10px;font-size:10px}.mobile-nav{scrollbar-width:none}
@media(max-width:950px){.term-grid{grid-template-columns:1fr}}@media(max-width:700px){.practice-tabs{gap:18px}.practice-tabs button{font-size:11px}.option .math-block{font-size:12px}.term-card{padding:20px}.term-count{font-size:10px}.term-count span{display:none}.term-card h2{font-size:17px}.term-card summary p{font-size:12px}}
.notation-help{margin:14px 0;border:1px solid var(--line);border-radius:6px;background:var(--bg);font-size:12px;padding:13px 15px}.notation-help summary{cursor:pointer;color:var(--accent);line-height:1.7}.notation-help summary>span{display:block;color:var(--muted);font:10px/1.7 var(--sans);margin-left:14px}.symbol-definitions{margin:15px 0 8px}.symbol-definitions>div{display:grid;grid-template-columns:72px 1fr;gap:12px;padding:12px 0;border-top:1px solid var(--line);min-width:0}.symbol-definitions dt{padding-top:2px;color:var(--accent);min-width:0}.symbol-definitions dd{margin:0;min-width:0;line-height:1.8}.symbol-definitions dd strong{font-weight:600;font-size:11px}.symbol-definitions dd p{margin:4px 0 7px;font-size:11px}.symbol-unit{color:var(--muted);font-size:10px}.notation-help>.text-link{font-size:10px}.symbol-grid{display:grid;grid-template-columns:1fr 1fr;gap:15px;margin-top:24px;align-items:start}.symbol-card{border:1px solid var(--line);border-radius:7px;padding:24px;background:var(--paper);min-width:0}.symbol-card-top{display:flex;align-items:center;justify-content:space-between;gap:15px;margin-bottom:20px;color:var(--accent)}.symbol-card-top>.symbol-unit{font:10px var(--sans);text-align:right}.symbol-card h2{font:600 15px/1.6 var(--sans);letter-spacing:-.2px;margin:0 0 12px}.symbol-card p{font-size:12px;line-height:1.9;color:var(--muted)}.symbol-card details{font-size:11px;border-top:1px solid var(--line);margin-top:18px;padding-top:14px}.symbol-card summary{cursor:pointer;color:var(--accent)}.symbol-card details p{font-size:11px}.empty-actions{display:flex;flex-wrap:wrap;justify-content:center;gap:12px;margin-top:20px}.empty-state h2{font:500 25px/1.4 var(--serif)}.empty-state p{line-height:1.8;font-size:12px}.practice-tabs{gap:20px}.practice-tabs button{font-size:12px}
@media(max-width:700px){.symbol-grid{grid-template-columns:1fr}.symbol-card{padding:21px}.symbol-definitions>div{grid-template-columns:58px 1fr;gap:10px}.notation-help{padding:12px}.practice-tabs{gap:18px}.practice-tabs button{font-size:11px}.symbol-definitions dt .katex{font-size:1em}}

.symbol-word{font:600 12px/1.6 var(--sans);overflow-wrap:anywhere}.symbol-definitions>.wide-symbol{grid-template-columns:1fr;gap:2px}.symbol-card-top>span:first-child{min-width:0}.symbol-card-top .symbol-word{font-size:13px}
.case-condition{padding:20px 22px;background:var(--bg);border:1px solid var(--line);border-radius:6px;margin-bottom:28px}.demo-card[open] .case-mistakes>summary{padding:8px 0;margin:0;border:0}
.case-condition .case-prompt{margin:10px 0 0}.demo-step{margin:32px 0;max-width:940px}.demo-step h3{display:flex;align-items:baseline;gap:12px;font-size:15px;line-height:1.6}.step-index{font:11px ui-monospace,monospace;color:var(--accent);flex-shrink:0}.demo-step p{margin-left:29px}.demo-step .case-table-wrap{margin-left:29px}
.case-table-wrap{max-width:100%;overflow-x:auto;margin:20px 0 24px;border:1px solid var(--line);border-radius:6px;scrollbar-width:thin}.case-table{width:100%;border-collapse:collapse;font-size:12px;line-height:1.65;text-align:left}.case-table caption{text-align:left;padding:12px 15px;background:var(--bg);font-size:11px;font-weight:600;color:var(--muted)}.case-table th,.case-table td{padding:11px 14px;border-top:1px solid var(--line);vertical-align:top}.case-table thead th{font-size:11px;color:var(--muted);background:var(--bg);font-weight:500}.case-table tbody th{font-weight:500;color:var(--text);min-width:145px}.case-table td{color:var(--muted);min-width:100px}.case-table .math-block{padding:4px!important;margin:0;background:transparent}.case-table .katex{font-size:1em}.case-table-wrap:focus-visible{outline:2px solid var(--accent);outline-offset:3px}
.answer-box>strong{display:block;font-size:12px;margin-bottom:10px}.answer-box>p{margin:0}.paper-guide{padding:20px 22px;margin:25px 0;background:var(--bg);border:1px solid var(--line);border-radius:6px}.paper-guide h3,.paper-guide h4{font-size:14px;margin:0 0 13px}.paper-guide .steps{margin-bottom:0}.case-mistakes{margin:24px 0;font-size:13px}.case-mistakes summary,.exam-solution summary,.exam-notes summary{cursor:pointer;color:var(--accent);padding:8px 0;font-size:12px;line-height:1.7}.case-mistakes .steps{margin-top:12px}
.exam-actions{display:flex;align-items:center;flex-wrap:wrap;gap:12px;margin:22px 0}.exam-actions>.muted{font-size:11px;line-height:1.8}.exam-task-heading{display:flex;align-items:baseline;justify-content:space-between;gap:15px}.exam-task-heading .eyebrow{font-size:10px;white-space:nowrap}.exam-condition{font-size:13px;line-height:1.9;white-space:pre-line;color:var(--muted)}.exam-notes{margin:20px 0 0}.exam-notes .note-label{margin-top:12px}.exam-review{margin-top:26px;padding-top:24px;border-top:1px solid var(--line)}.exam-review>h3{font-size:16px}.exam-review .discreet-note{margin:10px 0 18px}.exam-answer-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px 24px}.exam-answer .note-label{min-height:34px;line-height:1.6;color:var(--text)}.exam-answer .note-label>span{color:var(--muted)}.exam-answer input{width:100%;max-width:300px;min-width:0;border:1px solid var(--line);border-radius:5px;background:var(--bg);padding:11px 13px;color:var(--text);font-size:17px;margin:0}.answer-status{font-size:11px;line-height:1.7;color:var(--muted);margin:9px 0 0}.answer-status.is-correct{color:var(--green)}.answer-status.is-wrong{color:var(--accent)}.exam-solution{margin-top:24px;border-top:1px solid var(--line);padding-top:12px}.exam-solution>summary{font-size:13px}.exam-solution>.steps{margin-top:20px}.paper-rubric{border:0;border-top:1px solid var(--line);padding:18px 0 0;margin:22px 0 0;min-width:0}.paper-rubric legend{padding-right:12px;font-size:12px;font-weight:600}.paper-rubric label{display:flex;align-items:flex-start;gap:11px;margin:12px 0;font-size:12px;line-height:1.8;color:var(--muted);cursor:pointer}.paper-rubric input{width:17px;height:17px;flex:0 0 17px;margin:3px 0 0;accent-color:var(--accent)}.exam-print{display:none}
@media(max-width:700px){.case-condition{padding:16px}.demo-step p,.demo-step .case-table-wrap{margin-left:0}.demo-step h3{gap:9px}.case-table{font-size:11px}.case-table th,.case-table td{padding:9px 10px}.case-table tbody th{min-width:120px}.case-table td{min-width:85px}.paper-guide{padding:17px}.exam-answer-grid{grid-template-columns:1fr}.exam-task-heading{align-items:flex-start}.exam-task-heading h2{font-size:24px}.exam-setup .exam-specs{gap:17px}.exam-specs strong{font-size:28px}.exam-actions .button{font-size:11px}}
@media print{
  @page{size:A4;margin:15mm}
  .exam-screen{display:none!important}.exam-print{display:block!important;font-size:10pt;line-height:1.5}.exam-print header h1{font-size:22pt;margin:12pt 0}.exam-print header p{font-size:9pt;margin:9pt 0}.print-task{break-before:page}.exam-print header+.print-task{break-before:auto;margin-top:18pt}.print-task h2{font-size:16pt;margin:0 0 10pt}.print-task .exam-condition{font-size:10pt;line-height:1.65}.print-task .case-table-wrap{overflow:visible;border-radius:0;margin:12pt 0;break-inside:avoid}.print-task .case-table{font-size:9pt;table-layout:fixed;overflow-wrap:anywhere}.print-task .case-table th,.print-task .case-table td{padding:5pt;min-width:0}.print-task .case-table caption{padding:6pt;font-size:9pt}.paper-space{margin-top:15pt;break-inside:avoid}.paper-space>p{font-size:9pt;color:#666}.paper-line{height:6mm;border-bottom:1px solid #ddd}.print-task .math-block{overflow:visible}.exam-print input,.exam-print details{display:none!important}.demo-card[open]{break-inside:auto}.demo-step{break-inside:auto}.demo-step h3{break-after:avoid}.demo-step .case-table-wrap{overflow:visible;break-inside:avoid}.case-table{font-size:9pt}.paper-guide{break-inside:avoid}
}

/* Рядом: shared calm palette and accessible controls. */
:root{--bg:#f8f7f3;--paper:#fffefa;--text:#303638;--soft:#535c5e;--muted:#63696b;--accent:#80515a;--accent-hover:#68414a;--tint:#f0e6e6}
:root[data-theme=dark]{--bg:#202426;--paper:#282e30;--text:#edece7;--soft:#d2d5d4;--muted:#b3babc;--accent:#dbabb4;--accent-hover:#edc1ca;--tint:#413138}
.button,.icon-button,.nav-item,.course-tab,.option,input,select,textarea{border-radius:12px}.topic-card,.question-card,.formula-card,.demo-card,.term-card,.symbol-card,.course-bridge,.study-note,.exam-task{border-radius:16px}.button,.icon-button,.option,.practice-tabs button,input,select{min-height:44px}.network-nav{display:flex;align-items:center;gap:23px;padding:0 45px;min-height:50px;overflow-x:auto;white-space:nowrap;border-bottom:1px solid var(--line);font-size:11px}.network-nav>a{display:flex;align-items:center;min-height:48px;color:var(--muted)}.network-nav>a:first-child,.network-nav>a[aria-current],.network-nav>a:last-child{color:var(--accent)}.network-nav>a:hover{text-decoration:underline;text-underline-offset:4px}@media(max-width:1150px){.network-nav{padding-inline:30px}}@media(max-width:700px){.network-nav{padding-inline:22px;gap:20px;font-size:10px}}@media print{.network-nav{display:none!important}}@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}

/* Native MathML keeps formula layout compatible with the shared strict CSP. */
.katex>math{font-family:math,'Cambria Math','STIX Two Math',serif;font-size:1em;line-height:normal}.math-block>.katex{display:block}.math-block math[display=block]{display:block;margin:0;text-align:center}.math-inline math{display:inline}.math-block math{max-width:none}.math-block .katex{white-space:normal}

.valuation-bar-52{height:52px}.valuation-bar-82{height:82px}.valuation-bar-113{height:113px}.valuation-bar-160{height:160px}

/* Decorative markers keep text labels as the accessible meaning. */
.ui-emoji{display:inline-block;font-family:"Apple Color Emoji","Segoe UI Emoji","Noto Color Emoji",sans-serif;font-size:.85em;line-height:1;vertical-align:.03em;letter-spacing:0;font-style:normal;font-weight:400}.brand-mark{background:transparent}.identity-mark{display:block;width:40px;height:40px;flex-shrink:0}.mobile-identity-mark{display:block;width:28px;height:28px;flex-shrink:0}.feedback h3>.ui-emoji{margin-right:3px}@media(max-width:700px){.mobile-brand{align-items:center;gap:8px}}

.nav-line-icon{display:block;width:20px;height:20px;flex-shrink:0}