:root{--bg:#0f1218;--card:#1a1f2e;--card-hover:#22283a;--border:#2a3040;--text:#e8edf5;--text-dim:#8892a5;--accent:#5b8def;--accent-hover:#4a7ae0;--correct:#34d399;--wrong:#f87171;--warning:#fbbf24;--radius:10px}*{box-sizing:border-box;margin:0;padding:0}body{background:var(--bg);color:var(--text);min-height:100vh;font-family:-apple-system,PingFang SC,Noto Sans SC,Microsoft YaHei,sans-serif}a{color:var(--accent);text-decoration:none}a:hover{color:var(--accent-hover)}.page{max-width:960px;margin:0 auto;padding:20px}.loading-screen{min-height:100vh;color:var(--text-dim);flex-direction:column;justify-content:center;align-items:center;gap:16px;display:flex}.spinner{border:3px solid var(--border);border-top-color:var(--accent);border-radius:50%;width:36px;height:36px;animation:.8s linear infinite spin}@keyframes spin{to{transform:rotate(360deg)}}.card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);margin-bottom:16px;padding:20px}.card-header{justify-content:space-between;align-items:center;margin-bottom:12px;display:flex}.btn{cursor:pointer;border:none;border-radius:8px;align-items:center;gap:6px;padding:10px 20px;font-size:14px;font-weight:500;transition:all .2s;display:inline-flex}.btn-primary{background:var(--accent);color:#fff}.btn-primary:hover{background:var(--accent-hover)}.btn-secondary{background:var(--border);color:var(--text)}.btn-secondary:hover{background:var(--card-hover)}.btn-success{background:var(--correct);color:#000}.btn-danger{background:var(--wrong);color:#fff}.btn:disabled{opacity:.5;cursor:not-allowed}.btn-sm{padding:6px 14px;font-size:13px}.btn-outline{color:var(--text);border:2px solid var(--border);background:0 0}.btn-outline:hover{border-color:var(--accent);color:var(--accent)}.highlight-box{border-radius:4px;padding:2px 10px;font-size:14px;font-weight:600;display:inline-block}.form-group{margin-bottom:16px}.form-group label{color:var(--text-dim);margin-bottom:6px;font-size:14px;display:block}.form-input{border:1px solid var(--border);background:var(--bg);width:100%;color:var(--text);border-radius:8px;outline:none;padding:12px 14px;font-size:15px;transition:border-color .2s}.form-input:focus{border-color:var(--accent)}.form-input::placeholder{color:var(--text-dim)}select.form-input{cursor:pointer}.top-nav{background:var(--card);border-bottom:1px solid var(--border);z-index:100;align-items:center;gap:20px;padding:12px 24px;display:flex;position:sticky;top:0}.top-nav .logo{color:var(--text);font-size:18px;font-weight:700}.top-nav .logo span{color:var(--accent)}.top-nav a{color:var(--text-dim);padding:4px 8px;font-size:14px;transition:color .2s}.top-nav a:hover,.top-nav a.active{color:var(--text)}.top-nav .spacer{flex:1}.top-nav .user-info{color:var(--text-dim);font-size:13px}.top-nav .logout-btn{border:1px solid var(--border);color:var(--text-dim);cursor:pointer;background:0 0;border-radius:6px;padding:6px 14px;font-size:13px}.top-nav .logout-btn:hover{border-color:var(--wrong);color:var(--wrong)}.progress-bar{background:var(--border);border-radius:4px;height:8px;overflow:hidden}.progress-fill{background:linear-gradient(90deg, var(--accent), var(--correct));border-radius:4px;height:100%;transition:width .4s}.badge{border-radius:4px;padding:2px 8px;font-size:12px;font-weight:600;display:inline-block}.badge-green{color:var(--correct);background:#34d39933}.badge-yellow{color:var(--warning);background:#fbbf2433}.badge-red{color:var(--wrong);background:#f8717133}.badge-blue{color:var(--accent);background:#5b8def33}.grid-2{grid-template-columns:1fr 1fr;gap:16px;display:grid}.grid-3{grid-template-columns:1fr 1fr 1fr;gap:16px;display:grid}@media (width<=640px){.grid-2,.grid-3{grid-template-columns:1fr}}.stat-card{text-align:center;padding:20px}.stat-card .num{color:var(--accent);font-size:28px;font-weight:700}.stat-card .label{color:var(--text-dim);margin-top:4px;font-size:13px}.auth-page{justify-content:center;align-items:center;min-height:100vh;padding:20px;display:flex}.auth-card{width:100%;max-width:400px}.auth-card h1{text-align:center;margin-bottom:8px;font-size:24px}.auth-card h1 span{color:var(--accent)}.auth-card .subtitle{text-align:center;color:var(--text-dim);margin-bottom:24px;font-size:14px}.auth-card .auth-link{text-align:center;color:var(--text-dim);margin-top:16px;font-size:14px}.option-list{flex-direction:column;gap:10px;display:flex}.option-btn{background:var(--card);border:1px solid var(--border);cursor:pointer;color:var(--text);text-align:left;border-radius:8px;align-items:center;gap:12px;padding:12px 16px;font-size:15px;line-height:1.5;transition:all .2s;display:flex}.option-btn:hover{border-color:var(--accent);background:var(--card-hover)}.option-btn .letter{background:var(--border);border-radius:50%;flex-shrink:0;justify-content:center;align-items:center;width:28px;height:28px;font-size:13px;font-weight:600;display:inline-flex}.option-btn.selected{border-color:var(--accent);background:#5b8def14}.option-btn.selected .letter{background:var(--accent);color:#fff}.option-btn.correct{border-color:var(--correct)!important;background:#34d3991a!important}.option-btn.correct .letter{background:var(--correct)!important;color:#000!important}.option-btn.wrong{border-color:var(--wrong)!important;background:#f871711a!important}.option-btn.wrong .letter{background:var(--wrong)!important;color:#fff!important}.option-btn.disabled{cursor:default;opacity:.7}.q-text{margin-bottom:16px;font-size:16px;line-height:1.7}.q-tag{color:var(--text-dim);margin-bottom:8px;font-size:12px}.explanation-box{background:var(--bg);border-left:3px solid var(--accent);color:var(--text-dim);border-radius:8px;margin-top:16px;padding:14px 16px;font-size:14px;line-height:1.7}.explanation-box .label{color:var(--accent);margin-bottom:4px;font-size:12px;font-weight:600}.score-bar{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);flex-wrap:wrap;align-items:center;gap:16px;margin-bottom:20px;padding:14px 20px;display:flex}.score-bar .item{align-items:center;gap:6px;font-size:14px;display:flex}.score-bar .item .num{font-weight:700}.result-card{text-align:center;padding:40px}.result-card .big-num{margin-bottom:8px;font-size:48px;font-weight:700}.result-card .status{margin-bottom:8px;font-size:16px}.result-card .sub{color:var(--text-dim);margin-bottom:24px;font-size:14px}.module-card{cursor:pointer;transition:all .2s}.module-card:hover{border-color:var(--accent);background:var(--card-hover)}.module-card .top{justify-content:space-between;align-items:start;margin-bottom:8px;display:flex}.module-card .name{font-size:16px;font-weight:600}.module-card .desc{color:var(--text-dim);margin-bottom:12px;font-size:13px}.module-card .stats{color:var(--text-dim);flex-wrap:wrap;gap:16px;font-size:12px;display:flex}.module-card .stats span{white-space:nowrap}.history-table{border-collapse:collapse;width:100%}.history-table th{text-align:left;color:var(--text-dim);border-bottom:1px solid var(--border);padding:10px 12px;font-size:13px}.history-table td{border-bottom:1px solid var(--border);padding:10px 12px;font-size:14px}.history-table tr:hover td{background:#ffffff05}.page-header{margin-bottom:24px}.page-header h1{font-size:22px;font-weight:700}.page-header .sub{color:var(--text-dim);margin-top:4px;font-size:14px}.empty-state{text-align:center;color:var(--text-dim);padding:60px 20px}.empty-state .icon{margin-bottom:12px;font-size:48px}.mastery-checks{flex-wrap:wrap;gap:16px;margin-bottom:16px;display:flex}.mastery-check{color:var(--text-dim);align-items:center;gap:6px;font-size:13px;display:flex}.mastery-check .check{border-radius:50%;justify-content:center;align-items:center;width:18px;height:18px;font-size:11px;display:flex}.mastery-check .check.pass{color:var(--correct);background:#34d39933}.mastery-check .check.fail{color:var(--wrong);background:#f8717133}.fade-in{animation:.3s fadeIn}@keyframes fadeIn{0%{opacity:0;transform:translateY(8px)}to{opacity:1;transform:translateY(0)}}::-webkit-scrollbar{width:6px}::-webkit-scrollbar-track{background:var(--bg)}::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px}