:root{--bg:#ffffff;--fg:#1a1a1a;--muted:#666666;--border:#dddddd;--primary:#1a56db;--primary-dark:#14439e;--ok:#15803d;--err:#b91c1c;--warn:#c2620a;--mark:#f59e0b}*{box-sizing:border-box}body,html{margin:0;padding:0;background:var(--bg);color:var(--fg);font-family:Noto Sans TC,Microsoft JhengHei,PingFang TC,system-ui,-apple-system,sans-serif;font-size:18px;line-height:1.7;-webkit-user-select:none;-moz-user-select:none;user-select:none}input,textarea{-webkit-user-select:text;-moz-user-select:text;user-select:text}@media print{body *{visibility:hidden}}a{color:var(--primary);text-decoration:none}a:hover{text-decoration:underline}.container{max-width:1000px;margin:0 auto;padding:24px}.container-narrow{max-width:560px;margin:0 auto;padding:24px}.topbar{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:14px 24px;border-bottom:2px solid var(--border);background:#fafafa;position:-webkit-sticky;position:sticky;top:0;z-index:10}.topbar .brand{font-weight:700;font-size:20px}.topbar .user{color:var(--muted);font-size:15px}.topbar .actions{display:flex;gap:12px;align-items:center}.btn{display:inline-block;padding:10px 20px;font-size:17px;border:1px solid var(--primary);background:var(--primary);color:#fff;border-radius:8px;cursor:pointer;transition:background .15s}.btn:hover{background:var(--primary-dark);text-decoration:none}.btn:disabled{opacity:.5;cursor:not-allowed}.btn-secondary{background:#fff;color:var(--primary)}.btn-secondary:hover{background:#eef2ff}.btn-ghost{background:#fff;color:var(--fg);border-color:var(--border)}.btn-ghost:hover{background:#f5f5f5}.btn-danger{background:var(--err);border-color:var(--err)}.btn-danger:hover{background:#991b1b}.btn-block{display:block;width:100%}.field{margin-bottom:18px}.field label{display:block;font-weight:600;margin-bottom:6px}.field input,.field select{width:100%;padding:12px;font-size:17px;border:1px solid var(--border);border-radius:8px}.field input:focus,.field select:focus{outline:2px solid var(--primary);border-color:var(--primary)}.card{border:1px solid var(--border);border-radius:12px;padding:24px;margin-bottom:20px;background:#fff}h1{font-size:30px;margin:0 0 16px}h2{font-size:24px;margin:0 0 12px}h3{font-size:20px;margin:0 0 10px}.muted{color:var(--muted)}.error{color:var(--err)}.error,.success{font-weight:600;margin:10px 0}.success{color:var(--ok)}.center{text-align:center}.mt{margin-top:20px}.mb{margin-bottom:20px}.subject-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));grid-gap:16px;gap:16px}.subject-card{border:1px solid var(--border);border-radius:12px;padding:20px;display:flex;flex-direction:column;gap:8px}.subject-card .code{font-size:15px;color:var(--muted);font-weight:700}.subject-card .name{font-size:19px;font-weight:700}.subject-card .meta{color:var(--muted);font-size:15px}.exam-layout{display:grid;grid-template-columns:220px 1fr;grid-gap:24px;gap:24px;align-items:start}@media (max-width:800px){.exam-layout{grid-template-columns:1fr}}.timer{font-size:26px;font-weight:800;font-feature-settings:"tnum";font-variant-numeric:tabular-nums}.timer.warn{color:var(--warn)}.timer.danger{color:var(--err)}.qnav{display:grid;grid-template-columns:repeat(5,1fr);grid-gap:8px;gap:8px;position:-webkit-sticky;position:sticky;top:80px}.qnav button{aspect-ratio:1;font-size:16px;font-weight:700;border:1px solid var(--border);background:#fff;border-radius:8px;cursor:pointer}.qnav button.answered{background:var(--primary);color:#fff;border-color:var(--primary)}.qnav button.marked{border-color:var(--mark);box-shadow:inset 0 0 0 2px var(--mark)}.qnav button.current{outline:3px solid var(--fg)}.legend{display:flex;flex-wrap:wrap;gap:14px;margin-top:14px;font-size:14px;color:var(--muted)}.legend span{display:inline-flex;align-items:center;gap:6px}.legend .swatch{width:16px;height:16px;border-radius:4px;display:inline-block;border:1px solid var(--border)}.swatch.answered{background:var(--primary)}.swatch.marked{box-shadow:inset 0 0 0 2px var(--mark)}.question-stem{font-size:22px;font-weight:700;margin-bottom:20px;line-height:1.6}.option{display:flex;gap:12px;align-items:flex-start;padding:14px;border:1px solid var(--border);border-radius:10px;margin-bottom:12px;cursor:pointer;font-size:19px}.option:hover{background:#f5f7ff}.option.selected{border-color:var(--primary);background:#eef2ff}.option .letter{font-weight:800;flex-shrink:0}.exam-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:24px}.score-hero{text-align:center;padding:32px}.score-hero .score{font-size:72px;font-weight:800;line-height:1}.score-hero .pass{font-size:28px;font-weight:800;margin-top:8px}.score-hero .pass.yes{color:var(--ok)}.score-hero .pass.no{color:var(--err)}.stat-row{display:flex;gap:16px;justify-content:center;flex-wrap:wrap;margin-top:24px}.stat{border:1px solid var(--border);border-radius:10px;padding:16px 24px;text-align:center;min-width:120px}.stat .num{font-size:34px;font-weight:800}.stat .lbl{color:var(--muted);font-size:15px}.review-q{border:1px solid var(--border);border-radius:12px;padding:20px;margin-bottom:20px}.review-q .tag{display:inline-block;font-size:14px;padding:2px 10px;border-radius:999px;margin-bottom:10px;font-weight:700}.tag.correct{background:#dcfce7;color:var(--ok)}.tag.wrong{background:#fee2e2;color:var(--err)}.tag.unanswered{background:#f3f4f6;color:var(--muted)}.review-option{padding:10px 14px;border-radius:8px;margin-bottom:8px;border:1px solid transparent}.review-option.right{background:#dcfce7;border-color:var(--ok)}.review-option.user-wrong{background:#fee2e2;border-color:var(--err)}.explanation{margin-top:14px;padding:14px;background:#f9fafb;border-left:4px solid var(--primary);border-radius:6px}.topic-bar{margin-bottom:14px}.topic-bar .topic-name{display:flex;justify-content:space-between;font-size:16px;margin-bottom:4px}.bar-track{height:14px;background:#eee;border-radius:999px;overflow:hidden}.bar-fill{height:100%;background:var(--primary)}.bar-fill.weak{background:var(--err)}.bar-fill.mid{background:var(--warn)}