:root{--bg: #0b0f1a;--surface: #141b2e;--surface-2: #1b2440;--border: #2a3557;--text: #e7ecf7;--muted: #93a0bd;--accent: #a78bfa;--accent-2: #f472b6;--good: #34d399;--warn: #fbbf24;--radius: 14px;--mono: "SFMono-Regular", ui-monospace, "Cascadia Code", "Fira Code", Menlo, Consolas, monospace;--sans: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif}*{box-sizing:border-box}html,body{margin:0;background:var(--bg);color:var(--text);font-family:var(--sans);font-size:17px;line-height:1.6;-webkit-font-smoothing:antialiased}#test-canvas{display:none!important}a{color:var(--accent)}.page{max-width:820px;margin:0 auto;padding:24px 20px 80px}.btn{font:inherit;font-weight:600;color:#0b0f1a;background:linear-gradient(135deg,var(--accent),var(--accent-2));border:none;border-radius:999px;padding:11px 20px;cursor:pointer;transition:transform .08s ease,filter .15s ease}.btn:hover{filter:brightness(1.08)}.btn:active{transform:translateY(1px)}.btn:disabled{opacity:.45;cursor:not-allowed;filter:none}.btn-big{font-size:1.15rem;padding:14px 30px;margin-top:8px}.btn-ghost{background:transparent;color:var(--text);border:1px solid var(--border)}.btn-play{background:linear-gradient(135deg,var(--good),#10b981)}.btn-stop{background:var(--surface-2);color:var(--text);border:1px solid var(--border)}.link{background:none;border:none;color:var(--muted);font:inherit;cursor:pointer;padding:4px 0}.link:hover{color:var(--text)}.hero{text-align:center;padding:28px 0 20px}.hero-badge{display:inline-block;font-weight:600;font-size:.85rem;color:var(--accent);background:var(--surface);border:1px solid var(--border);border-radius:999px;padding:5px 14px;margin-bottom:18px}.hero h1{font-size:clamp(1.8rem,6vw,2.8rem);line-height:1.15;margin:0 0 14px;background:linear-gradient(120deg,#fff,var(--accent));-webkit-background-clip:text;background-clip:text;color:transparent}.hero-sub{color:var(--muted);max-width:560px;margin:0 auto 18px}.hero-progress{color:var(--muted);font-size:.9rem;margin-top:14px}.callout{background:var(--surface);border:1px solid var(--border);border-left:4px solid var(--accent);border-radius:var(--radius);padding:16px 18px;margin:8px 0 32px;font-size:.98rem}.kbd-inline{background:var(--surface-2);border:1px solid var(--border);border-radius:6px;padding:1px 8px;font-size:.9em;white-space:nowrap}.section-title{font-size:1.3rem;margin:32px 0 14px}.muted{color:var(--muted)}.grid{display:grid;gap:14px;grid-template-columns:repeat(auto-fill,minmax(210px,1fr))}.card{text-align:left;font:inherit;color:var(--text);cursor:pointer;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:16px;position:relative;transition:transform .1s ease,border-color .15s ease}.card:hover{transform:translateY(-3px);border-color:var(--accent)}.card-top{display:flex;justify-content:space-between;align-items:center}.card-emoji{font-size:1.9rem}.card-check{color:var(--good);font-weight:800;font-size:1.1rem}.card-num{color:var(--muted);font-size:.8rem;margin-top:10px}.card-title{font-size:1.12rem;font-weight:700;margin:2px 0 6px}.card-concept{display:inline-block;font-size:.78rem;color:var(--accent);background:#a78bfa1f;border-radius:999px;padding:2px 10px}.cheat{margin-top:8px}.cheat-grid{display:grid;gap:8px;margin-top:12px}.cheat-row{display:flex;gap:14px;align-items:baseline;flex-wrap:wrap;background:var(--surface);border:1px solid var(--border);border-radius:10px;padding:10px 14px}.cheat-row code{font-family:var(--mono);color:var(--accent-2);background:var(--surface-2);padding:2px 8px;border-radius:6px;font-size:.92rem}.cheat-row span{color:var(--muted)}.topnav{display:flex;justify-content:space-between;align-items:center;margin-bottom:20px}.topnav-count{color:var(--muted);font-size:.85rem}.chapter-head{display:flex;gap:16px;align-items:center;margin-bottom:8px}.chapter-emoji{font-size:3rem;line-height:1}.chapter-head h1{font-size:1.8rem;margin:2px 0 0}.chapter-concept-tag{display:inline-block;font-size:.8rem;font-weight:600;color:var(--accent);background:#a78bfa1f;border-radius:999px;padding:3px 12px}.prose p{margin:12px 0}.bridge{display:grid;grid-template-columns:1fr auto 1fr;gap:12px;align-items:center;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin:22px 0}.bridge-col p{margin:6px 0 0;font-size:.95rem}.bridge-label{font-weight:700;font-size:.9rem}.bridge-music .bridge-label{color:var(--accent-2)}.bridge-code .bridge-label{color:var(--accent)}.bridge-arrow{font-size:1.6rem;color:var(--muted)}.strudel{border:1px solid var(--border);border-radius:var(--radius);overflow:hidden;margin:22px 0;background:#0d1220}.strudel-toolbar{display:flex;gap:10px;align-items:center;flex-wrap:wrap;padding:10px 12px;background:var(--surface);border-bottom:1px solid var(--border)}.strudel-toolbar .btn{padding:8px 16px;font-size:.95rem}.strudel-hint{color:var(--muted);font-size:.82rem;margin-left:auto}.strudel-hint kbd{font-family:var(--mono);background:var(--surface-2);border:1px solid var(--border);border-radius:5px;padding:0 6px}.strudel-host>div{min-height:120px}.strudel-host .cm-editor{font-size:15px}.strudel-note{padding:10px 14px;color:var(--muted);font-size:.9rem;margin:0}.strudel-note--error{color:var(--warn)}.tasks{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:8px 20px 16px;margin:22px 0}.tasks h2{font-size:1.15rem}.tasks ol{margin:0;padding-left:22px}.tasks li{margin:8px 0}.tip{display:flex;gap:12px;align-items:flex-start;background:#fbbf2414;border:1px solid rgba(251,191,36,.35);border-radius:var(--radius);padding:14px 16px;margin:18px 0}.tip-icon{font-size:1.3rem}.tip p{margin:0;font-size:.95rem}.chapter-nav{display:flex;justify-content:space-between;gap:12px;margin-top:34px;flex-wrap:wrap}.foot{color:var(--muted);text-align:center;font-size:.85rem;margin-top:48px}.foot p{margin:0}.foot p+p{margin-top:8px;opacity:.75}@media(max-width:560px){body{font-size:16px}.bridge{grid-template-columns:1fr;text-align:center}.bridge-arrow{transform:rotate(90deg)}.strudel-hint{display:none}.chapter-nav .btn,.chapter-nav .btn-ghost{flex:1}}.topbar{display:flex;justify-content:flex-end;margin-bottom:4px}.lang-switcher{display:inline-flex;align-items:center;gap:6px}.lang-globe{font-size:1rem;line-height:1}.lang-select{font:inherit;font-size:.88rem;color:var(--text);background:var(--surface);border:1px solid var(--border);border-radius:999px;padding:6px 12px;cursor:pointer}.lang-select:hover{border-color:var(--accent)}[dir=rtl] .hero-sub,[dir=rtl] .callout,[dir=rtl] .prose p,[dir=rtl] .tasks li,[dir=rtl] .bridge-col p{text-align:right}[dir=rtl] .tasks ol{padding-left:0;padding-right:22px}[dir=rtl] .strudel-hint{margin-left:0;margin-right:auto}code,.strudel,.strudel-host,.strudel-host .cm-editor,.strudel-hint kbd{direction:ltr}[dir=rtl] code{unicode-bidi:isolate;text-align:left}