:root{color-scheme:light;--background: #f5f5f4;--background-elevated: #fafaf9;--surface: #ffffff;--surface-alt: #fafaf9;--border: #e7e5e4;--border-strong: #d6d3d1;--text: #1c1917;--text-muted: #57534e;--text-subtle: #8a8580;--on-primary: #ffffff;--primary: #ea580c;--primary-dark: #c2410c;--primary-soft: #fff1e7;--primary-glow: rgb(234 88 12 / .18);--success: #047857;--success-soft: #ecfdf5;--danger: #b91c1c;--danger-soft: #fef2f2;--warning: #b45309;--warning-soft: #fffbeb;--info: #1d4ed8;--info-soft: #eff6ff;--header-from: #f97316;--header-to: #ea580c;--header-deep: #c2410c;--chart-correct: #047857;--chart-wrong: #b91c1c;--chart-single: #ea580c;--mastery-1: #fb923c;--mastery-2: #ea580c;--mastery-3: #c2410c;--mastery-4: #7c2d12;--grade-1: #86b6ef;--grade-2: #5598e7;--grade-3: #2a78d6;--grade-4: #184f95;--grid: #e7e5e4;--cat-estimating: #ea580c;--cat-estimating-soft: #fff1e7;--cat-materials: #0d9488;--cat-materials-soft: #f0fdfa;--cat-structures: #4f46e5;--cat-structures-soft: 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var(--ease)}.btn:hover{text-decoration:none;filter:brightness(1.05)}.btn:active{transform:scale(.98)}.btn:disabled{opacity:.55;cursor:not-allowed;filter:none;transform:none}.btn.secondary{background:var(--surface);color:var(--text);border-color:var(--border-strong)}.btn.ghost{background:transparent;color:var(--text-muted);border-color:var(--border)}.btn.danger{background:var(--danger-soft);color:var(--danger);border-color:var(--danger)}.btn.block{width:100%}.btn-row{display:flex;gap:10px;flex-wrap:wrap}.study{display:flex;flex-direction:column;gap:18px;max-width:720px;margin:0 auto}.study-head{display:flex;align-items:center;justify-content:space-between;gap:12px}.study-head h1{font-size:18px;font-weight:700;letter-spacing:-.02em}.session-pills{display:flex;flex-wrap:wrap;gap:8px}.session-pill{display:inline-flex;align-items:center;gap:6px;padding:5px 10px;border-radius:999px;background:var(--surface);border:1px solid 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a{font-size:14px;font-weight:600;color:var(--text-muted);text-decoration:none}.footer-nav a:hover{color:var(--primary-dark);text-decoration:underline}.footer-note{max-width:var(--max-width);margin:16px auto 0;padding-top:12px;border-top:1px solid var(--border)}@media(max-width:720px){.topbar .nav{display:none}.bottom-nav{display:flex}.main{padding:20px 16px 28px}.site-footer{padding-bottom:calc(20px + var(--bottom-nav-h) + env(safe-area-inset-bottom,0px))}.summary-strip{grid-template-columns:repeat(2,1fr)}.brand-tag{display:none}.cat-tabs-wrap{top:calc(var(--nav-h) - 2px)}}@media(max-width:520px){h1{font-size:22px}.main{padding-left:14px;padding-right:14px}.hero{padding:18px 16px;border-radius:var(--radius-lg)}.deck-list{grid-template-columns:1fr}.flashcard{padding:20px 16px;border-radius:var(--radius-lg)}.prompt{font-size:17px}.grades{grid-template-columns:repeat(2,1fr)}.grade-btn{min-height:64px}.topbar-inner{padding:10px 14px}}@media(min-width:900px){.deck-list{grid-template-columns:repeat(auto-fill,minmax(300px,1fr))}}@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}@media(pointer:coarse){.cat-tab{min-height:44px}.option{min-height:56px}}.switch-row{display:flex;align-items:center;justify-content:space-between;gap:16px}.switch{position:relative;flex:none;width:50px;height:30px;display:inline-block}.switch input{position:absolute;top:0;right:0;bottom:0;left:0;width:100%;height:100%;margin:0;opacity:0;cursor:pointer}.switch input:disabled{cursor:not-allowed}.switch>span{position:absolute;top:0;right:0;bottom:0;left:0;border-radius:999px;background:var(--border-strong);transition:background .15s ease;pointer-events:none}.switch>span:after{content:"";position:absolute;top:3px;left:3px;width:24px;height:24px;border-radius:50%;background:#fff;box-shadow:0 1px 2px #00000040;transition:transform .15s ease}.switch input:checked+span{background:var(--primary)}.switch input:checked+span:after{transform:translate(20px)}.switch input:disabled+span{opacity:.5}.switch input:focus-visible+span{outline:2px solid var(--primary);outline-offset:2px}.chip-row{display:flex;flex-wrap:wrap;gap:8px}.chip-btn{min-height:40px;padding:0 16px;border-radius:999px;border:1px solid var(--border);background:var(--surface);color:var(--text-muted);font-size:14px;font-weight:600}.chip-btn:hover:not(:disabled){border-color:var(--border-strong)}.chip-btn.active{background:var(--primary-soft);border-color:var(--primary);color:var(--primary-dark)}.chip-btn:disabled{opacity:.5;cursor:not-allowed}.quiz-card{display:flex;flex-direction:column;gap:14px}.quiz-head h2{margin-bottom:2px}.quiz-options{display:grid;gap:8px;grid-template-columns:repeat(auto-fit,minmax(96px,1fr))}.quiz-option{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:1px;min-height:60px;padding:8px;border-radius:var(--radius);border:1px solid var(--border);background:var(--surface-alt);color:var(--text);text-align:center;transition:border-color .12s ease,transform .12s ease}.quiz-option:hover{text-decoration:none;border-color:var(--primary);transform:translateY(-1px)}.quiz-option strong{font-size:15px;font-weight:700}.quiz-option span{font-size:12px;color:var(--text-subtle)}.exam-clock{display:inline-flex;align-items:center;justify-content:center;min-width:68px;min-height:40px;padding:0 12px;border-radius:999px;border:1px solid var(--border-strong);background:var(--surface-alt);color:var(--text);font-size:16px;font-weight:700;font-variant-numeric:tabular-nums}.exam-clock.urgent{background:var(--danger-soft);border-color:var(--danger);color:var(--danger)}