:root{--bg: #f5f6fb;--surface: #ffffff;--surface-2: #f0f2f9;--text: #0d1326;--muted: #5b6478;--border: #e4e7f0;--accent: #157a3a;--accent-weak: #e7f4ec;--accent-text: #ffffff;--gold: #f5b91e;--shadow: 0 1px 2px rgba(13, 19, 38, .05), 0 8px 24px rgba(13, 19, 38, .06);--again: #e5484d;--hard: #f5a623;--good: #2ba24c;--easy: #3e63dd;--correct: #2ba24c;--wrong: #e5484d;--r-sm: 8px;--r-md: 14px;--r-lg: 20px;--sp: 16px;--maxw: 600px;--tap: 52px;--safe-b: env(safe-area-inset-bottom, 0px);--safe-t: env(safe-area-inset-top, 0px)}@media(prefers-color-scheme:dark){:root{--bg: #0b1020;--surface: #151b2e;--surface-2: #1c2238;--text: #eef1f8;--muted: #99a2b8;--border: #262d44;--accent: #2fc15c;--accent-weak: #11271a;--accent-text: #07150d;--gold: #ffc83d;--shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 10px 30px rgba(0, 0, 0, .35)}}*{box-sizing:border-box}html,body,#root{height:100%}body{margin:0;background:var(--bg);color:var(--text);font-family:ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;overscroll-behavior-y:none}button{font:inherit;cursor:pointer}a{color:var(--accent)}.shell{display:flex;flex-direction:column;min-height:100dvh;max-width:var(--maxw);margin:0 auto;background:var(--bg)}.topbar{position:sticky;top:0;z-index:10;display:flex;align-items:center;justify-content:space-between;gap:12px;padding:calc(var(--safe-t) + 10px) var(--sp) 10px;background:color-mix(in srgb,var(--bg) 88%,transparent);-webkit-backdrop-filter:saturate(150%) blur(10px);backdrop-filter:saturate(150%) blur(10px);border-bottom:1px solid var(--border)}.topbar h1{font-size:1rem;margin:0;font-weight:700;letter-spacing:-.01em}.topbar .sub{font-size:.78rem;color:var(--muted)}.main{flex:1;display:flex;flex-direction:column;padding:var(--sp);gap:var(--sp)}.content-scroll{flex:1;overflow-y:auto;-webkit-overflow-scrolling:touch}.surface{background:var(--surface);border:1px solid var(--border);border-radius:var(--r-lg);box-shadow:var(--shadow)}.pad{padding:var(--sp)}.badge{display:inline-flex;align-items:center;gap:6px;font-size:.72rem;font-weight:600;padding:4px 10px;border-radius:999px;background:var(--accent-weak);color:var(--accent);border:1px solid color-mix(in srgb,var(--accent) 22%,transparent)}.badge.muted{background:var(--surface-2);color:var(--muted);border-color:var(--border)}.prompt{font-size:1.18rem;line-height:1.5;font-weight:550;white-space:pre-wrap;word-break:break-word}.answer-box{margin-top:14px;padding:14px;border-radius:var(--r-md);background:color-mix(in srgb,var(--good) 12%,var(--surface));border:1px solid color-mix(in srgb,var(--good) 35%,transparent)}.answer-box .label{font-size:.72rem;font-weight:700;color:var(--good);text-transform:uppercase;letter-spacing:.04em}.answer-box .val{font-size:1.05rem;font-weight:650;margin-top:4px}.explanation{margin-top:12px;color:var(--muted);font-size:.95rem;line-height:1.55;white-space:pre-wrap}.choices{display:flex;flex-direction:column;gap:10px;margin-top:18px}.choice{display:flex;align-items:flex-start;gap:12px;text-align:left;padding:14px;min-height:var(--tap);border-radius:var(--r-md);border:1.5px solid var(--border);background:var(--surface);color:var(--text);transition:border-color .12s,background .12s,transform .06s}.choice:active{transform:scale(.99)}.choice .key{flex:none;width:28px;height:28px;display:grid;place-items:center;border-radius:8px;background:var(--surface-2);font-weight:700;font-size:.85rem}.choice.correct{border-color:var(--correct);background:color-mix(in srgb,var(--correct) 12%,var(--surface))}.choice.correct .key{background:var(--correct);color:#fff}.choice.wrong{border-color:var(--wrong);background:color-mix(in srgb,var(--wrong) 12%,var(--surface))}.choice.wrong .key{background:var(--wrong);color:#fff}.choice:disabled{cursor:default}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:var(--tap);padding:0 18px;border-radius:var(--r-md);border:1.5px solid var(--border);background:var(--surface);color:var(--text);font-weight:650;transition:transform .06s,opacity .12s,background .12s}.btn:active{transform:scale(.98)}.btn:disabled{opacity:.55;cursor:default}.btn-primary{background:var(--accent);color:var(--accent-text);border-color:var(--accent);width:100%;font-size:1.05rem}.btn-block{width:100%}.btn-ghost{background:transparent;border-color:transparent;color:var(--muted)}.actionbar{position:sticky;bottom:0;padding:12px var(--sp) calc(12px + var(--safe-b));background:color-mix(in srgb,var(--bg) 90%,transparent);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-top:1px solid var(--border)}.grade-bar{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}.grade-btn{display:flex;flex-direction:column;align-items:center;gap:2px;min-height:60px;border-radius:var(--r-md);border:none;color:#fff;font-weight:700;transition:transform .06s,filter .12s}.grade-btn:active{transform:scale(.96)}.grade-btn .lbl{font-size:.95rem}.grade-btn .hint{font-size:.68rem;font-weight:600;opacity:.9}.grade-btn.again{background:var(--again)}.grade-btn.hard{background:var(--hard)}.grade-btn.good{background:var(--good)}.grade-btn.easy{background:var(--easy)}.progress{height:6px;border-radius:999px;background:var(--surface-2);overflow:hidden}.progress>span{display:block;height:100%;background:var(--accent);transition:width .25s ease}.field{display:flex;flex-direction:column;gap:6px}.field label{font-size:.82rem;font-weight:600;color:var(--muted)}.input{min-height:var(--tap);padding:0 14px;border-radius:var(--r-md);border:1.5px solid var(--border);background:var(--surface);color:var(--text);font-size:1rem}.input:focus{outline:none;border-color:var(--accent)}.stat-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px}.stat{padding:16px}.stat .num{font-size:1.9rem;font-weight:800;letter-spacing:-.02em}.stat .cap{font-size:.78rem;color:var(--muted);margin-top:2px}.section-title{font-size:.95rem;font-weight:700;margin:4px 0}.row{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:10px 0;border-bottom:1px solid var(--border)}.row:last-child{border-bottom:none}.bar-track{height:8px;border-radius:999px;background:var(--surface-2);overflow:hidden;flex:1}.bar-track>span{display:block;height:100%;border-radius:999px}.heatmap{display:grid;grid-auto-flow:column;grid-template-rows:repeat(7,1fr);gap:3px;overflow-x:auto;padding-bottom:4px}.heat-cell{width:13px;height:13px;border-radius:3px;background:var(--surface-2)}.bottomnav{position:sticky;bottom:0;display:grid;grid-template-columns:repeat(2,1fr);border-top:1px solid var(--border);background:var(--surface);padding-bottom:var(--safe-b)}.navbtn{background:none;border:none;padding:12px;display:flex;flex-direction:column;align-items:center;gap:3px;color:var(--muted);font-size:.72rem;font-weight:600}.navbtn.active{color:var(--accent)}.center-screen{min-height:100dvh;display:grid;place-items:center;padding:var(--sp)}.muted{color:var(--muted)}.error-banner{padding:12px 14px;border-radius:var(--r-md);background:color-mix(in srgb,var(--wrong) 14%,var(--surface));border:1px solid color-mix(in srgb,var(--wrong) 40%,transparent);color:var(--wrong);font-size:.9rem}.spin{width:28px;height:28px;border-radius:50%;border:3px solid var(--border);border-top-color:var(--accent);animation:spin .8s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}.stack{display:flex;flex-direction:column;gap:var(--sp)}.no-select{-webkit-user-select:none;user-select:none;-webkit-touch-callout:none}.done-emoji{font-size:3rem;text-align:center}.toast{position:fixed;left:50%;bottom:calc(90px + var(--safe-b));transform:translate(-50%);background:var(--wrong);color:#fff;padding:10px 16px;border-radius:999px;font-size:.85rem;font-weight:600;box-shadow:var(--shadow);z-index:50}