:root{--paper:#eef2f2;--paper-2:#e2e9e8;--card:#f7f9f8;--ink:#172033;--ink-dim:#526072;--line:#c9d3d2;--line-strong:#a8b6b4;--accent:#d9773a;--accent-ink:#fffaf5;--accent-2:#3c6e71;--success:#2f8f5b;--success-bg:#e1f3e8;--danger:#c0435a;--danger-bg:#fbe7ec;--shadow:rgba(23,32,51,.1);color-scheme:light}@media(prefers-color-scheme:dark){:root:not([data-theme=light]){--paper:#10161f;--paper-2:#161f2a;--card:#141c26;--ink:#e7ecec;--ink-dim:#a3b1bd;--line:#2a3644;--line-strong:#3c4b5a;--accent:#e28a51;--accent-ink:#1a1206;--accent-2:#74b0b2;--success:#5cc08e;--success-bg:#153524;--danger:#e37c92;--danger-bg:#3a1822;--shadow:rgba(0,0,0,.45);color-scheme:dark}}:root[data-theme=dark]{--paper:#10161f;--paper-2:#161f2a;--card:#141c26;--ink:#e7ecec;--ink-dim:#a3b1bd;--line:#2a3644;--line-strong:#3c4b5a;--accent:#e28a51;--accent-ink:#1a1206;--accent-2:#74b0b2;--success:#5cc08e;--success-bg:#153524;--danger:#e37c92;--danger-bg:#3a1822;--shadow:rgba(0,0,0,.45);color-scheme:dark}*{box-sizing:border-box}body{margin:0;background:linear-gradient(var(--paper-2) 1px,transparent 1px) 0 0/100% 28px,linear-gradient(90deg,var(--paper-2) 1px,transparent 1px) 0 0/28px 100%,var(--paper);background-attachment:local;color:var(--ink);font-family:Karla,system-ui,-apple-system,sans-serif;font-size:16px;line-height:1.5}h1,h2,h3{font-family:Newsreader,Georgia,serif;text-wrap:balance;margin:0}.mono{font-family:IBM Plex Mono,ui-monospace,Menlo,monospace}.hand{font-family:Caveat,cursive}a{color:var(--accent-2)}button{font-family:inherit}:focus-visible{outline:2px solid var(--accent);outline-offset:2px}@media(prefers-reduced-motion:reduce){*{animation-duration:.001ms!important;transition-duration:.001ms!important}}.wrap{max-width:960px;margin:0 auto;padding:0 20px 64px}header.top{position:sticky;top:0;z-index:20;background:color-mix(in srgb,var(--paper) 88%,transparent);-webkit-backdrop-filter:blur(6px);backdrop-filter:blur(6px);border-bottom:1px solid var(--line)}.top-inner{max-width:960px;margin:0 auto;padding:14px 20px;display:flex;align-items:center;gap:20px;flex-wrap:wrap}.brand{display:flex;align-items:baseline;gap:8px;margin-right:auto}.brand .mark{font-size:1.5rem}.brand h1{font-size:1.4rem;font-weight:600;letter-spacing:-.01em}.brand .tag{font-size:.8rem;color:var(--ink-dim)}.daily-streak{font-size:.82rem;font-weight:600;color:var(--accent-2);background:color-mix(in srgb,var(--accent-2) 12%,var(--card));border:1px solid var(--line);border-radius:999px;padding:6px 12px;white-space:nowrap}.daily-streak.risk{color:var(--ink-dim);background:var(--paper-2)}nav.tabs{display:flex;gap:4px;background:var(--paper-2);padding:4px;border-radius:999px}nav.tabs button{border:none;background:transparent;color:var(--ink-dim);padding:8px 18px;border-radius:999px;font-size:.92rem;font-weight:600;cursor:pointer}nav.tabs button.active{background:var(--accent);color:var(--accent-ink)}main{padding-top:8px}.hero{padding:38px 0 8px}.hero h2{font-size:2.1rem;font-weight:600}.hero p.lede{max-width:60ch;color:var(--ink-dim);font-size:1.05rem;margin-top:10px}.card{background:var(--card);border:1px solid var(--line);border-radius:14px;box-shadow:0 6px 16px var(--shadow)}.viz{padding:20px 20px 24px;margin-top:24px}.viz-head{display:flex;align-items:baseline;justify-content:space-between;gap:12px;flex-wrap:wrap;margin-bottom:6px}.viz-head h3{font-size:1.15rem;font-weight:600}.viz-body{display:grid;grid-template-columns:minmax(0,1.5fr) minmax(220px,1fr);gap:20px;align-items:start}@media(max-width:680px){.viz-body{grid-template-columns:1fr}}svg.plot{width:100%;height:auto;display:block;touch-action:none}.axis-line{stroke:var(--line-strong);stroke-width:1.5}.grid-line{stroke:var(--line);stroke-width:1}.curve{fill:none;stroke:var(--accent-2);stroke-width:2.5;stroke-linecap:round}.tangent{fill:none;stroke:var(--accent);stroke-width:2.5}.secant{fill:none;stroke:var(--ink-dim);stroke-width:1.6;stroke-dasharray:5 4}.pt{fill:var(--accent);stroke:var(--card);stroke-width:2;cursor:grab}.pt:active{cursor:grabbing}.pt2{fill:var(--ink-dim);stroke:var(--card);stroke-width:2}.riemann-rect{fill:var(--accent);fill-opacity:.35;stroke:var(--accent);stroke-width:1}text.tick{fill:var(--ink-dim);font-size:9px;font-family:IBM Plex Mono,monospace}.vec-u,.vec-u-head{stroke:var(--accent);fill:var(--accent)}.vec-v,.vec-v-head{stroke:var(--accent-2);fill:var(--accent-2)}.vec-sum,.vec-sum-head{stroke:var(--ink-dim);fill:var(--ink-dim)}.vec-u,.vec-v{stroke-width:2.5}.vec-sum{stroke-width:2;stroke-dasharray:6 4}.vec-helper{stroke:var(--line-strong);stroke-width:1;stroke-dasharray:3 3}circle.tip{fill:var(--card);stroke-width:2;cursor:grab}circle.tip-u{stroke:var(--accent)}circle.tip-v{stroke:var(--accent-2)}circle.tip:active{cursor:grabbing}.vec-u-label{color:var(--accent);font-weight:700}.vec-v-label{color:var(--accent-2);font-weight:700}.mat-square{fill:none;stroke:var(--ink-dim);stroke-width:1.5;stroke-dasharray:4 3}.mat-para{fill:var(--accent);fill-opacity:.18;stroke:var(--accent-2);stroke-width:2}.mat-para.flipped{fill:var(--danger);fill-opacity:.18;stroke:var(--danger)}.controls{display:flex;flex-direction:column;gap:14px;margin-top:14px}.ctrl label{display:flex;justify-content:space-between;font-size:.85rem;color:var(--ink-dim);margin-bottom:4px}.ctrl label b{color:var(--ink);font-family:IBM Plex Mono,monospace;font-weight:500}input[type=range]{width:100%;accent-color:var(--accent)}.readout{display:flex;flex-direction:column;gap:10px}.readout .stat{display:flex;justify-content:space-between;align-items:baseline;padding:8px 10px;background:var(--paper-2);border-radius:8px}.readout .stat .k{font-size:.82rem;color:var(--ink-dim)}.readout .stat .v{font-family:IBM Plex Mono,monospace;font-weight:500}.readout .limit{padding:10px 12px;border-radius:8px;background:var(--success-bg);color:var(--success);font-family:IBM Plex Mono,monospace;font-size:.85rem;text-align:center;transition:opacity .2s}.readout .limit.far{opacity:.35;background:var(--paper-2);color:var(--ink-dim)}.rules-head{margin-top:44px}.rules-head h3{font-size:1.3rem;font-weight:600}.rules-head p{color:var(--ink-dim);margin-top:4px}.rule-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:14px;margin-top:18px}.rule-card{padding:16px 18px;text-align:left;cursor:pointer;transition:transform .12s,box-shadow .12s}.rule-card:hover{transform:translateY(-2px);box-shadow:0 10px 22px var(--shadow)}.rule-card .num{font-size:.72rem;letter-spacing:.06em;text-transform:uppercase;color:var(--accent-2);font-weight:700}.rule-card h4{font-family:Newsreader,serif;font-size:1.08rem;font-weight:600;margin:4px 0 8px}.rule-card .f{font-size:1rem;color:var(--ink);background:var(--paper-2);padding:8px 10px;border-radius:6px;display:inline-block;line-height:1.9}.rule-card .f mjx-container{color:var(--ink)}.mat-given mjx-container{color:var(--ink)}.mat-given{font-size:1.15rem}.practice-head{padding:30px 0 4px}.practice-head h2{font-size:1.8rem;font-weight:600}.stat-strip{display:flex;gap:10px;flex-wrap:wrap;margin:16px 0 20px}.pill{background:var(--card);border:1px solid var(--line);border-radius:999px;padding:7px 14px;font-size:.85rem;display:flex;gap:6px;align-items:center}.pill b{font-family:IBM Plex Mono,monospace}.level-row{display:flex;gap:8px;overflow-x:auto;padding-bottom:8px;margin-bottom:18px}.level-chip{flex:0 0 auto;border:1px solid var(--line);background:var(--card);color:var(--ink-dim);padding:9px 14px;border-radius:10px;cursor:pointer;font-size:.85rem;font-weight:600;display:flex;align-items:center;gap:6px;white-space:nowrap}.level-chip.active{border-color:var(--accent);color:var(--ink);background:color-mix(in srgb,var(--accent) 12%,var(--card))}.level-chip .ring{width:16px;height:16px;border-radius:50%;border:2px solid var(--line-strong);display:inline-flex;align-items:center;justify-content:center;font-size:9px}.level-chip.mastered .ring{background:var(--success);border-color:var(--success);color:#fff}.level-chip.mixed{border-style:dashed}.level-chip.mixed .ring{border:none;font-size:12px}.level-chip.mixed.active{border-color:var(--accent-2);background:color-mix(in srgb,var(--accent-2) 14%,var(--card))}.mixed-tag{color:var(--ink-dim);text-transform:none;letter-spacing:normal;font-weight:600}.problem-card{padding:26px 26px 22px}.problem-card .eyebrow{font-size:.78rem;text-transform:uppercase;letter-spacing:.07em;color:var(--accent-2);font-weight:700}.problem-card .fx{font-family:IBM Plex Mono,monospace;font-size:1.55rem;margin:10px 0 20px}.streak-dots{display:flex;gap:6px;margin-bottom:18px}.streak-dots span{width:9px;height:9px;border-radius:50%;background:var(--line)}.streak-dots span.on{background:var(--accent)}.answer-row{display:flex;gap:10px;flex-wrap:wrap;align-items:center}.answer-row .prefix{font-family:IBM Plex Mono,monospace;color:var(--ink-dim)}input.answer{font-family:IBM Plex Mono,monospace;font-size:1.05rem;padding:10px 12px;border-radius:8px;border:1.5px solid var(--line-strong);background:var(--paper);color:var(--ink);flex:1 1 220px;min-width:0}input.answer:focus{border-color:var(--accent)}input.answer:disabled{opacity:.7}.btn{border:none;border-radius:8px;padding:10px 18px;font-weight:600;font-size:.92rem;cursor:pointer}.btn-primary{background:var(--accent);color:var(--accent-ink)}.btn-primary:disabled{opacity:.5;cursor:not-allowed}.btn-ghost{background:transparent;color:var(--ink-dim);border:1px solid var(--line-strong)}.btn:hover{filter:brightness(1.06)}.hint-text{margin-top:12px;font-size:.88rem;color:var(--ink-dim);font-style:italic}.syntax-help{margin-top:10px;font-size:.78rem;color:var(--ink-dim)}.feedback{margin-top:18px;padding:14px 16px;border-radius:10px;display:none}.feedback.show{display:block}.feedback.ok{background:var(--success-bg);color:var(--success)}.feedback.bad{background:var(--danger-bg);color:var(--danger)}.feedback .fhead{font-weight:700;display:flex;align-items:center;gap:8px;flex-wrap:wrap}.feedback .note{font-family:Caveat,cursive;font-size:1.15rem}.feedback .explain{margin-top:10px;color:var(--ink);font-size:.92rem;line-height:1.6}.feedback .explain .step{display:block;margin-top:4px}.feedback-actions{margin-top:14px;display:flex;gap:10px;flex-wrap:wrap}footer{max-width:960px;margin:40px auto 0;padding:16px 20px 40px;color:var(--ink-dim);font-size:.8rem;display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap}footer button{background:none;border:none;color:var(--ink-dim);text-decoration:underline;cursor:pointer;font-size:.8rem;padding:0}.spread-body{grid-template-columns:minmax(0,1.7fr) minmax(220px,1fr)}.sigma-band{fill:var(--accent);fill-opacity:.12;stroke:var(--accent);stroke-opacity:.35;stroke-dasharray:4 4}.mean-line{stroke:var(--accent);stroke-width:2}.mean-label{fill:var(--accent);font-size:11px;font-family:IBM Plex Mono,monospace}.data-dot{fill:var(--accent-2);stroke:var(--card);stroke-width:2;cursor:grab}.data-dot:active{cursor:grabbing}.dev-square{fill:var(--accent-2);fill-opacity:.22;stroke:var(--accent-2);stroke-width:1.5}.sq-caption{fill:var(--ink-dim);font-size:11px}.axis-line.faint{stroke:var(--line)}.freq-bar{fill:var(--accent-2);fill-opacity:.75;transition:height .18s ease,y .18s ease}.freq-bar.hot{fill:var(--accent);fill-opacity:1}.theory-line{stroke:var(--accent);stroke-width:2;stroke-dasharray:6 4}.die-face{fill:var(--ink);font-size:20px}.viz-actions{display:flex;gap:8px;flex-wrap:wrap;margin-top:12px}.btn.sm{padding:7px 12px;font-size:.82rem}.viz-note{margin-top:12px;font-size:.85rem;color:var(--ink-dim);line-height:1.55}.viz-note b{color:var(--ink)}.step-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(215px,1fr));gap:14px;margin-top:18px}.step-card{padding:16px 18px}.step-card .num,.worked-card .num{font-size:.72rem;letter-spacing:.06em;text-transform:uppercase;color:var(--accent-2);font-weight:700}.step-card h4,.worked-card h4{font-family:Newsreader,serif;font-size:1.05rem;font-weight:600;margin:4px 0 8px}.step-card .f{background:var(--paper-2);padding:8px 10px;border-radius:6px;display:inline-block}.step-card p{margin:10px 0 0;font-size:.86rem;color:var(--ink-dim);line-height:1.55}.worked-card{padding:16px 18px;grid-column:1 / -1}.worked-card p{margin:8px 0 0;font-size:.9rem;line-height:1.9}.worked-card .aside{margin-top:14px;padding:12px 14px;background:var(--paper-2);border-radius:8px;font-size:.86rem;line-height:1.6;color:var(--ink-dim)}.worked-card .aside b{color:var(--ink)}.problem-card .scenario{margin:8px 0 14px;font-size:1.02rem;line-height:1.6;max-width:62ch}.chip-row{display:flex;gap:8px;flex-wrap:wrap;align-items:center;margin-bottom:16px}.data-chip{background:var(--paper-2);border:1px solid var(--line);border-radius:8px;padding:6px 12px;font-size:.95rem}.data-chip.num{font-size:1.05rem;font-weight:500}.chip-unit{font-size:.82rem;color:var(--ink-dim)}.given-list{list-style:none;padding:0;margin:0 0 16px;display:flex;gap:8px;flex-wrap:wrap}.given-list li{background:var(--paper-2);border:1px solid var(--line);border-radius:8px;padding:6px 12px;font-size:.92rem}.prob-table{border-collapse:collapse;margin:0 0 18px;font-size:.9rem}.prob-table th,.prob-table td{border:1px solid var(--line);padding:7px 14px;text-align:center;font-family:IBM Plex Mono,monospace;font-weight:400}.prob-table th{background:var(--paper-2);color:var(--ink-dim);font-size:.8rem;text-transform:uppercase;letter-spacing:.04em}.prob-table td.rowhead{background:var(--paper-2);color:var(--ink-dim);text-align:left;font-family:Karla,sans-serif}.ws-builder{padding:22px 24px;margin-top:20px;display:flex;flex-direction:column;gap:18px}.ws-field{display:flex;flex-direction:column;gap:6px}.ws-field>label{font-size:.8rem;color:var(--ink-dim);font-weight:600}.ws-input{font-family:inherit;font-size:.95rem;padding:9px 11px;border-radius:8px;border:1.5px solid var(--line-strong);background:var(--paper);color:var(--ink)}.ws-input:focus{border-color:var(--accent)}.ws-input.short{width:110px}.ws-row{display:flex;gap:20px;flex-wrap:wrap;align-items:flex-start}.ws-field.checks{gap:9px;padding-top:22px}.ws-check{display:flex;align-items:center;gap:7px;font-size:.88rem;cursor:pointer}.ws-check.disabled{opacity:.45;cursor:not-allowed}.ws-check input{accent-color:var(--accent);width:16px;height:16px}.ws-topics{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:16px}.ws-topic{border:1px solid var(--line);border-radius:10px;padding:12px 14px;background:var(--paper-2)}.ws-topic-head{display:flex;align-items:center;gap:8px;background:none;border:none;cursor:pointer;font-size:.92rem;font-weight:700;color:var(--ink);padding:0 0 10px}.ws-topic-head .box{width:17px;height:17px;border-radius:5px;border:2px solid var(--line-strong);display:inline-flex;align-items:center;justify-content:center;font-size:11px;color:#fff}.ws-topic-head.all .box{background:var(--success);border-color:var(--success)}.ws-topic-head.some .box{background:var(--accent);border-color:var(--accent)}.ws-chapters{display:flex;flex-wrap:wrap;gap:6px}.ws-chip{border:1px solid var(--line);background:var(--card);color:var(--ink-dim);padding:6px 10px;border-radius:999px;font-size:.78rem;font-weight:600;cursor:pointer}.ws-chip.on{border-color:var(--accent);background:color-mix(in srgb,var(--accent) 16%,var(--card));color:var(--ink)}.ws-actions{display:flex;gap:12px;align-items:center;flex-wrap:wrap}.ws-warn{font-size:.85rem;color:var(--danger)}.ws-count{font-size:.85rem;color:var(--ink-dim)}.ws-sheet{margin-top:28px;display:flex;flex-direction:column;gap:24px}.ws-paper{background:#fff;color:#111;border:1px solid var(--line);border-radius:12px;box-shadow:0 6px 16px var(--shadow);padding:42px 46px}.ws-head{border-bottom:2px solid #111;padding-bottom:14px;margin-bottom:22px}.ws-head h1{font-family:Newsreader,Georgia,serif;font-size:1.7rem;font-weight:600;color:#111}.ws-meta{display:flex;gap:26px;margin-top:14px;flex-wrap:wrap}.ws-line{flex:1 1 220px;font-size:.9rem;color:#333;display:flex;align-items:baseline;gap:8px}.ws-line.short{flex:0 1 170px}.ws-line i{flex:1;border-bottom:1px solid #999;display:block;height:1em}.ws-sub{margin:12px 0 0;font-size:.82rem;color:#666}.ws-questions{margin:0;padding-left:26px}.ws-q{margin-bottom:26px;break-inside:avoid;page-break-inside:avoid}.ws-q-head{display:flex;gap:10px;align-items:baseline;flex-wrap:wrap}.ws-q-chapter{font-size:.66rem;text-transform:uppercase;letter-spacing:.06em;font-weight:700;color:#555;border:1px solid #bbb;border-radius:4px;padding:1px 6px}.ws-q-instruction{font-size:.88rem;color:#444}.ws-q-body{margin-top:8px}.ws-fx{font-family:IBM Plex Mono,monospace;font-size:1.2rem;color:#111}.ws-scenario{margin:0;font-size:.97rem;line-height:1.55;max-width:64ch;color:#111}.ws-chips,.ws-data,.ws-given{margin:8px 0 0;display:flex;gap:7px;flex-wrap:wrap;align-items:center}.ws-chips span,.ws-data span,.ws-given span{border:1px solid #bbb;border-radius:6px;padding:3px 9px;font-size:.88rem;font-family:IBM Plex Mono,monospace}.ws-data em{font-size:.8rem;color:#666;font-style:normal}.ws-table{border-collapse:collapse;margin-top:10px;font-size:.86rem}.ws-table th,.ws-table td{border:1px solid #999;padding:5px 12px;text-align:center;font-family:IBM Plex Mono,monospace;font-weight:400}.ws-table th{background:#f0f0f0;font-size:.76rem;text-transform:uppercase}.ws-table td.rowhead{background:#f7f7f7;text-align:left;font-family:Karla,sans-serif}.ws-answer-line{display:flex;align-items:baseline;gap:10px;margin-top:14px}.ws-answer-label{font-family:IBM Plex Mono,monospace;font-size:.95rem;color:#111;white-space:nowrap}.ws-rule{flex:1;border-bottom:1px solid #111;height:1em}.ws-work{border:1px dashed #ccc;border-radius:6px;margin-top:10px}.ws-key .ws-head h1{font-size:1.4rem}.ws-key-list{margin:0;padding-left:26px}.ws-key-item{margin-bottom:18px;break-inside:avoid;page-break-inside:avoid;font-size:.9rem}.ws-key-answer{display:flex;gap:8px;align-items:baseline;flex-wrap:wrap}.ws-key-label{font-family:IBM Plex Mono,monospace;color:#444}.ws-key-answer b{font-family:IBM Plex Mono,monospace;font-size:1rem;color:#111}.ws-key-answer em{color:#777;font-size:.85rem}.ws-key-work{margin-top:6px;color:#333;font-size:.85rem;line-height:1.6;padding-left:2px}.ws-key-work .step{display:block;margin-top:3px}.ws-paper mjx-container{color:#111!important}@media print{@page{margin:16mm 14mm}body{background:#fff!important;color:#000}header.top,footer,.no-print,nav.tabs,.ws-builder{display:none!important}main{padding:0!important}.wrap{max-width:none;padding:0;margin:0}.ws-sheet{margin:0;gap:0;display:block}.ws-paper{border:none!important;border-radius:0!important;box-shadow:none!important;padding:0!important;background:#fff!important;color:#000!important}.ws-key{break-before:page;page-break-before:always}.ws-work{border-color:#ddd}}
