*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}:root{--bg: #0f172a;--surface: #1e293b;--surface-2: #263248;--border: #334155;--accent: #6366f1;--accent-hover: #818cf8;--correct: #22c55e;--correct-bg: rgba(34, 197, 94, .12);--correct-border: rgba(34, 197, 94, .4);--wrong: #ef4444;--wrong-bg: rgba(239, 68, 68, .12);--wrong-border: rgba(239, 68, 68, .4);--neutral-bg: rgba(99, 102, 241, .08);--neutral-border: rgba(99, 102, 241, .3);--text: #f1f5f9;--text-muted: #94a3b8;--text-dim: #64748b;--radius: 12px;--radius-sm: 8px}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;background:var(--bg);color:var(--text);min-height:100vh;line-height:1.6}.app{min-height:100vh;display:flex;flex-direction:column;align-items:center;padding:24px 16px}.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:32px}.btn{display:inline-flex;align-items:center;gap:8px;padding:12px 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var(--border)}.instant-feedback.correct{border-color:var(--correct-border);background:var(--correct-bg)}.instant-feedback.wrong{border-color:var(--wrong-border);background:var(--wrong-bg)}.instant-feedback-title{font-weight:700;font-size:15px;margin-bottom:4px}.instant-feedback.correct .instant-feedback-title{color:var(--correct)}.instant-feedback.wrong .instant-feedback-title{color:var(--wrong)}.instant-feedback-body{font-size:14px;color:var(--text-muted);line-height:1.6}.instant-feedback-body strong{color:var(--text)}.home-config .config-label{display:block;font-size:14px;font-weight:600;color:var(--text-muted);text-transform:uppercase;letter-spacing:.06em;margin-bottom:16px}.toggle-row{display:flex;align-items:center;justify-content:space-between;margin-top:20px;padding-top:20px;border-top:1px solid 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16px;color:var(--accent-hover);border-color:var(--neutral-border)}.practice-btn:hover{background:var(--neutral-bg);color:var(--accent-hover);border-color:var(--accent)}.practice-panel{background:var(--surface-2);border:1.5px solid var(--accent);border-radius:var(--radius);padding:18px 20px}.practice-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:14px}.practice-label{font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.08em;color:var(--accent-hover)}.practice-close{background:transparent;border:none;color:var(--text-dim);cursor:pointer;font-size:14px;line-height:1;padding:3px 6px;border-radius:4px}.practice-close:hover{color:var(--text);background:var(--surface)}.practice-question{font-size:1rem;font-weight:600;line-height:1.5;color:var(--text);margin-bottom:16px}.practice-options{display:flex;flex-direction:column;gap:8px;margin-bottom:12px}.practice-result{padding:10px 14px;border-radius:var(--radius-sm);font-size:14px;font-weight:600;margin-bottom:12px}.practice-result.correct{background:var(--correct-bg);border:1px solid var(--correct-border);color:var(--correct)}.practice-result.wrong{background:var(--wrong-bg);border:1px solid var(--wrong-border);color:var(--wrong)}.practice-footer{display:flex;justify-content:flex-end}.study{max-width:640px;width:100%;margin:auto;display:flex;flex-direction:column;gap:28px}.study-header{display:flex;flex-direction:column;gap:16px}.study-header-top{display:flex}.study-header-text{text-align:center}.study-title{font-size:2rem;font-weight:800;line-height:1.2;margin-bottom:10px;background:linear-gradient(135deg,#f1f5f9,#94a3b8);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.study-desc{color:var(--text-muted);font-size:15px;line-height:1.6}.study-grid{display:flex;flex-direction:column;gap:8px}.study-card{display:flex;align-items:center;gap:16px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:16px 20px;cursor:pointer;text-align:left;transition:all .12s 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.study-card-title{color:#4ade80}.study-card-check{color:#4ade80;font-size:18px;font-weight:700;flex-shrink:0}.article-view{max-width:680px;width:100%;margin:auto;display:flex;flex-direction:column;gap:20px}.article-back-btn{padding:8px 16px;font-size:13px}.article-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);overflow:hidden}.article-header{padding:28px 32px 24px;border-bottom:1px solid var(--border);background:var(--surface-2)}.article-category-badge{display:inline-block;background:var(--neutral-bg);border:1px solid var(--neutral-border);color:var(--accent-hover);font-size:11px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;padding:3px 10px;border-radius:100px;margin-bottom:12px}.article-title{font-size:1.7rem;font-weight:800;line-height:1.25;margin-bottom:6px}.article-subtitle{color:var(--text-muted);font-size:15px}.article-body{padding:32px}.article-body>*:first-child{margin-top:0}.article-h2{font-size:1.1rem;font-weight:700;color:var(--text);margin-top:28px;margin-bottom:10px}.article-h3{font-size:.95rem;font-weight:700;color:var(--accent-hover);margin-top:16px;margin-bottom:6px}.article-p{color:var(--text-muted);line-height:1.75;margin-bottom:10px;font-size:15px}.article-p strong{color:var(--text)}.article-p em{color:var(--text);font-style:italic}.article-hr{border:none;border-top:1px solid var(--border);margin:22px 0}.article-blockquote{border-left:3px solid var(--accent);padding:12px 18px;background:var(--neutral-bg);border-radius:0 var(--radius-sm) var(--radius-sm) 0;color:var(--text);font-weight:600;font-size:1rem;margin-bottom:10px}.article-blockquote strong{color:var(--accent-hover)}.article-list{padding-left:22px;color:var(--text-muted);display:flex;flex-direction:column;gap:5px;margin-bottom:10px;font-size:15px}.article-list li{line-height:1.65}.article-list strong{color:var(--text)}.article-list em{color:var(--text);font-style:italic}.article-table-wrap{overflow-x:auto;margin-bottom:10px;border-radius:var(--radius-sm);border:1px solid var(--border)}.article-table{width:100%;border-collapse:collapse;font-size:14px}.article-table th{text-align:left;padding:10px 14px;background:var(--surface-2);color:var(--text-muted);font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.06em;border-bottom:1px solid var(--border);white-space:nowrap}.article-table td{padding:10px 14px;color:var(--text-muted);border-bottom:1px solid var(--border);vertical-align:top}.article-table td strong{color:var(--text)}.article-table tr:last-child td{border-bottom:none}.examples-wrapper{margin:20px 0}.examples-trigger{display:flex;align-items:center;gap:10px;width:100%;background:var(--neutral-bg);border:1.5px solid var(--neutral-border);border-radius:var(--radius);padding:13px 18px;color:var(--accent-hover);font-weight:600;font-size:14px;cursor:pointer;transition:all .15s ease}.examples-trigger:hover,.examples-trigger-open{background:#6366f124;border-color:var(--accent)}.examples-trigger-icon{font-size:14px;flex-shrink:0}.examples-trigger-count{font-size:11px;font-weight:700;background:#6366f133;padding:2px 8px;border-radius:100px}.examples-trigger-score{font-size:11px;font-weight:700;background:var(--correct-bg);border:1px solid var(--correct-border);color:var(--correct);padding:2px 8px;border-radius:100px}.examples-trigger-chevron{margin-left:auto;font-size:12px;opacity:.7}.examples-connector{width:2px;height:14px;background:var(--accent);margin-left:22px;border-radius:0 0 2px 2px}.examples-panel{border:1.5px solid var(--accent);border-radius:var(--radius);background:var(--surface-2);overflow:hidden}.examples-panel-header{display:flex;align-items:center;gap:10px;padding:12px 18px;border-bottom:1px solid var(--border)}.examples-panel-label{font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.08em;color:var(--accent-hover);flex:1}.examples-close{background:transparent;border:none;color:var(--text-dim);cursor:pointer;font-size:13px;padding:3px 6px;border-radius:4px;line-height:1}.examples-close:hover{color:var(--text);background:var(--border)}.examples-questions{display:flex;flex-direction:column;gap:0}.example-question{padding:18px 18px 14px;border-bottom:1px solid var(--border)}.example-question:last-child{border-bottom:none}.example-q-num{font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.07em;color:var(--text-dim);margin-bottom:6px}.example-q-text{font-size:1rem;font-weight:600;line-height:1.5;color:var(--text);margin-bottom:12px}.example-options{display:flex;flex-direction:column;gap:8px;margin-bottom:0}.example-feedback{margin-top:12px;padding:12px 14px;border-radius:var(--radius-sm);font-size:14px}.example-feedback.correct{background:var(--correct-bg);border:1px solid var(--correct-border)}.example-feedback.wrong{background:var(--wrong-bg);border:1px solid var(--wrong-border)}.example-feedback-title{font-weight:700;margin-bottom:4px;font-size:13px}.example-feedback.correct .example-feedback-title{color:var(--correct)}.example-feedback.wrong .example-feedback-title{color:var(--wrong)}.example-feedback-body{color:var(--text-muted);line-height:1.6}.example-submit-row{display:flex;justify-content:flex-end;margin-top:12px}.example-submit-btn{padding:9px 22px;font-size:14px}.examples-panel-footer{display:flex;align-items:center;justify-content:space-between;padding:12px 18px;border-top:1px solid var(--border);background:var(--surface)}.examples-final-score{font-size:14px;font-weight:600;color:var(--text-muted)}.examples-footer-actions{display:flex;gap:8px;align-items:center}.examples-reset-btn,.examples-finish-btn{padding:6px 14px;font-size:13px}.auth-screen{min-height:100vh;display:flex;align-items:center;justify-content:center;padding:24px}.auth-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:40px 36px;width:100%;max-width:380px;text-align:center}.auth-logo{font-size:2.5rem;margin-bottom:12px}.auth-title{font-size:1.4rem;font-weight:700;color:var(--text);margin:0 0 6px}.auth-subtitle{font-size:14px;color:var(--text-muted);margin:0 0 28px}.auth-tabs{display:flex;background:var(--surface-2);border-radius:8px;padding:3px;margin-bottom:24px}.auth-tab{flex:1;padding:8px;font-size:14px;font-weight:500;border-radius:6px;background:transparent;border:none;color:var(--text-muted);cursor:pointer;transition:all .12s ease}.auth-tab.active{background:var(--accent);color:#fff}.auth-form{display:flex;flex-direction:column;gap:16px;text-align:left}.auth-field{display:flex;flex-direction:column;gap:6px}.auth-label{font-size:13px;font-weight:500;color:var(--text-muted)}.auth-input{background:var(--surface-2);border:1px solid var(--border);border-radius:8px;padding:10px 14px;font-size:14px;color:var(--text);outline:none;transition:border-color .12s ease}.auth-input:focus{border-color:var(--accent)}.auth-error{font-size:13px;color:#f87171;background:#f871711a;border:1px solid rgba(248,113,113,.25);border-radius:6px;padding:8px 12px}.auth-submit{width:100%;padding:12px;font-size:15px;margin-top:4px}.home-user-bar{display:flex;align-items:center;justify-content:space-between;padding:0 0 20px;max-width:480px;width:100%;margin:0 auto}.home-user-name{font-size:13px;color:var(--text-muted);font-weight:500}.home-logout-btn{padding:5px 12px;font-size:12px}.home-history{max-width:480px;width:100%;margin:0 auto;padding-top:8px}.home-history-label{font-size:12px;font-weight:600;color:var(--text-dim);text-transform:uppercase;letter-spacing:.06em;margin-bottom:10px}.history-item{display:flex;align-items:center;justify-content:space-between;background:var(--surface);border:1px solid var(--border);border-radius:8px;padding:10px 14px;margin-bottom:8px}.history-item-info{display:flex;align-items:center;gap:10px}.history-score{font-size:15px;font-weight:700;color:var(--text)}.history-pct{font-size:13px;font-weight:500;color:var(--text-muted)}.history-date{font-size:12px;color:var(--text-dim)}.history-review-btn{padding:5px 12px;font-size:12px}.short-answer-row{margin-bottom:16px}.short-answer-input{width:100%;background:var(--surface-2);border:1px solid var(--border);border-radius:8px;padding:14px 16px;font-size:1rem;color:var(--text);outline:none;transition:border-color .12s ease;box-sizing:border-box}.short-answer-input:focus{border-color:var(--accent)}.short-answer-input:disabled{opacity:.7}.review-short-body{padding:12px 16px}.review-short-answer{background:var(--surface-2);border-radius:8px;padding:12px 16px;border-left:3px solid var(--border)}.review-short-answer.is-correct{border-left-color:#22c55e}.review-short-answer.is-wrong{border-left-color:#ef4444}.calculator{background:var(--surface-2);border:1px solid var(--border);border-radius:var(--radius);padding:12px;width:220px}.calc-display-row{display:flex;align-items:center;justify-content:flex-end;gap:8px;padding:8px 12px;background:var(--bg);border-radius:6px;margin-bottom:10px;min-height:44px}.calc-op-hint{font-size:16px;color:var(--accent);font-weight:600;min-width:16px}.calc-display{font-size:20px;font-weight:600;color:var(--text);word-break:break-all;text-align:right}.calc-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:5px}.calc-btn{padding:10px 6px;border-radius:6px;border:none;background:var(--surface);color:var(--text);font-size:15px;font-weight:500;cursor:pointer;transition:background .1s}.calc-btn:hover{background:var(--border)}.calc-btn:active{background:var(--accent);color:#fff}.calc-btn-op{background:#6366f11f;color:var(--accent-hover);font-weight:600}.calc-btn-op:hover{background:var(--accent);color:#fff}.calc-btn-fn{font-size:12px;color:var(--text-muted)}.calc-btn-eq{background:var(--accent);color:#fff;font-weight:700}.calc-btn-eq:hover{background:var(--accent-hover)}.calc-btn-zero{grid-column:span 2}.quiz-calc-panel{display:flex;justify-content:flex-end;padding:0 0 12px}.quiz-calc-toggle{padding:10px 14px;font-size:18px;flex-shrink:0}.quiz-calc-toggle.active{background:#6366f126;border-color:var(--accent)}.examples-header-actions{display:flex;align-items:center;gap:8px}.examples-calc-btn{padding:4px 8px;font-size:16px}.examples-calc-btn.active{background:#6366f126;border-color:var(--accent)}.examples-calc-panel{padding:12px 16px;border-bottom:1px solid var(--border);display:flex;justify-content:flex-start}::-webkit-scrollbar{width:6px}::-webkit-scrollbar-track{background:var(--bg)}::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px}::-webkit-scrollbar-thumb:hover{background:var(--text-dim)}