:root{--bg:#f1f5f9;--card:#ffffff;--text:#0f172a;--muted:#64748b;--border:#e2e8f0;--primary:#0f766e;--primary-weak:#ccfbf1;--correct:#16a34a;--correct-bg:#dcfce7;--wrong:#dc2626;--wrong-bg:#fee2e2;--shadow:0 1px 3px rgba(15,23,42,0.08),0 1px 2px rgba(15,23,42,0.04)}*{box-sizing:border-box}body,html{margin:0;padding:0}body{background:var(--bg);color:var(--text);font-family:-apple-system,BlinkMacSystemFont,Segoe UI,PingFang SC,Hiragino Sans GB,Microsoft YaHei,sans-serif;line-height:1.6;-webkit-font-smoothing:antialiased}a{color:inherit;text-decoration:none}.container{max-width:780px;margin:0 auto;padding:20px 16px 64px}.hero{text-align:center;padding:40px 0 24px}.hero h1{font-size:26px;margin:0 0 8px}.hero p{color:var(--muted);margin:0;font-size:15px}.mode-grid{display:grid;grid-gap:14px;gap:14px;margin-top:24px}.mode-card{display:flex;align-items:center;justify-content:space-between;background:var(--card);border:1px solid var(--border);border-radius:14px;padding:18px 20px;box-shadow:var(--shadow);transition:transform .12s ease,box-shadow .12s ease}.mode-card:hover{transform:translateY(-2px);box-shadow:0 6px 18px rgba(15,23,42,.1)}.mode-card .m-title{font-size:17px;font-weight:600}.mode-card .m-sub{color:var(--muted);font-size:13px;margin-top:2px}.mode-card .m-count{background:var(--primary-weak);color:var(--primary);font-weight:700;border-radius:999px;padding:6px 14px;font-size:14px;white-space:nowrap}.footer-note{text-align:center;color:var(--muted);font-size:12px;margin-top:40px;line-height:1.8}.topbar{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:16px}.topbar .back{color:var(--primary);font-size:14px;font-weight:600}.topbar .title{font-size:15px;font-weight:600}.topbar .score{font-size:13px;color:var(--muted)}.progress-wrap{background:var(--border);border-radius:999px;height:8px;overflow:hidden;margin-bottom:8px}.progress-bar{height:100%;background:var(--primary);transition:width .25s ease}.progress-text{font-size:13px;color:var(--muted);margin-bottom:16px;display:flex;justify-content:space-between}.card{background:var(--card);border:1px solid var(--border);border-radius:16px;padding:22px 20px;box-shadow:var(--shadow)}.q-meta{display:flex;gap:8px;align-items:center;margin-bottom:12px;flex-wrap:wrap}.badge{font-size:12px;padding:3px 10px;border-radius:999px;background:var(--primary-weak);color:var(--primary);font-weight:600}.badge.cat{background:#eef2ff;color:#4338ca}.q-stem{font-size:17px;font-weight:600;margin:0 0 18px}.options{flex-direction:column}.option,.options{display:flex;gap:10px}.option{align-items:flex-start;border:1.5px solid var(--border);border-radius:12px;padding:12px 14px;cursor:pointer;background:#fff;transition:border-color .12s ease,background .12s ease;text-align:left;width:100%;font-size:15px;color:var(--text)}.option:hover{border-color:var(--primary)}.option .letter{flex:0 0 auto;width:26px;height:26px;border-radius:999px;background:var(--bg);color:var(--muted);display:flex;align-items:center;justify-content:center;font-weight:700;font-size:13px}.option.selected{border-color:var(--primary);background:var(--primary-weak)}.option.selected .letter{background:var(--primary);color:#fff}.option.correct{border-color:var(--correct);background:var(--correct-bg)}.option.correct .letter{background:var(--correct);color:#fff}.option.wrong{border-color:var(--wrong);background:var(--wrong-bg)}.option.wrong .letter{background:var(--wrong);color:#fff}.option:disabled{cursor:default}.result-line{margin-top:16px;padding:12px 14px;border-radius:12px;font-size:14px;font-weight:600}.result-line.ok{background:var(--correct-bg);color:var(--correct)}.result-line.no{background:var(--wrong-bg);color:var(--wrong)}.actions{display:flex;gap:10px;margin-top:20px}.btn{flex:1 1;border:none;border-radius:12px;padding:13px;font-size:15px;font-weight:600;cursor:pointer;transition:opacity .12s ease}.btn:disabled{opacity:.45;cursor:not-allowed}.btn.primary{background:var(--primary);color:#fff}.btn.ghost{background:#fff;color:var(--text);border:1.5px solid var(--border)}.hint{font-size:13px;color:var(--muted);margin-top:12px}.finish,.hint{text-align:center}.finish{padding:30px 10px}.finish .big{font-size:40px;font-weight:800;color:var(--primary)}.finish .sub{color:var(--muted);margin:6px 0 24px}