@import"https://fonts.googleapis.com/css2?family=Nunito:wght@400;600;700;800;900&display=swap";:root{--bg: #f0f2f5;--sidebar-bg: #1a1d2e;--sidebar-text: #c4c9d4;--sidebar-active: #ffffff;--sidebar-w: 280px;--content-bg: #ffffff;--card-shadow: 0 2px 12px rgba(0,0,0,.06);--card-shadow-hover: 0 8px 24px rgba(0,0,0,.1);--radius: 12px;--radius-lg: 16px;--font: "Nunito", "Segoe UI", sans-serif;--transition: .2s ease;--math-color: #f59e0b;--micro-color: #3b82f6;--macro-color: #10b981}*{margin:0;padding:0;box-sizing:border-box}body{font-family:var(--font);background:var(--bg);min-height:100vh;color:#2d2d3a;display:flex}.sidebar{width:var(--sidebar-w);min-height:100vh;background:var(--sidebar-bg);color:var(--sidebar-text);position:fixed;top:0;left:0;z-index:50;overflow-y:auto;transition:transform var(--transition);display:flex;flex-direction:column}.sidebar-brand{padding:24px 20px;border-bottom:1px solid rgba(255,255,255,.06)}.sidebar-brand h1{font-size:1.3rem;font-weight:900;color:#fff;letter-spacing:-.3px}.sidebar-brand span{font-size:.75rem;color:var(--sidebar-text);display:block;margin-top:2px}.sidebar-nav{flex:1;padding:12px 0}.nav-group{margin-bottom:4px}.nav-group-header{display:flex;align-items:center;gap:8px;padding:10px 20px;font-size:.7rem;font-weight:800;text-transform:uppercase;letter-spacing:1.2px;cursor:pointer;-webkit-user-select:none;user-select:none;transition:color var(--transition)}.nav-group-header:hover{color:#fff}.nav-group-header .chevron{margin-left:auto;font-size:.6rem;transition:transform var(--transition)}.nav-group.collapsed .chevron{transform:rotate(-90deg)}.nav-group.collapsed .nav-items{display:none}.nav-group[data-category=math] .nav-group-header{color:var(--math-color)}.nav-group[data-category=micro] .nav-group-header{color:var(--micro-color)}.nav-group[data-category=macro] .nav-group-header{color:var(--macro-color)}.nav-item{display:flex;align-items:center;gap:10px;padding:9px 20px 9px 32px;font-size:.88rem;font-weight:600;cursor:pointer;transition:all var(--transition);border-left:3px solid transparent;color:var(--sidebar-text)}.nav-item:hover{color:#fff;background:#ffffff0a}.nav-item.active{color:#fff;background:#ffffff14;border-left-color:var(--math-color)}.nav-group[data-category=micro] .nav-item.active{border-left-color:var(--micro-color)}.nav-group[data-category=macro] .nav-item.active{border-left-color:var(--macro-color)}.nav-item .nav-icon{font-size:1.1rem;width:24px;text-align:center}.hamburger{display:none;position:fixed;top:14px;left:14px;z-index:100;background:var(--sidebar-bg);color:#fff;border:none;border-radius:10px;width:42px;height:42px;font-size:1.3rem;cursor:pointer;box-shadow:0 2px 12px #0003}.sidebar-overlay{display:none;position:fixed;top:0;right:0;bottom:0;left:0;background:#0006;z-index:40}.main{margin-left:var(--sidebar-w);flex:1;min-height:100vh;padding:32px}.landing{max-width:900px;margin:0 auto}.landing-header{margin-bottom:28px}.landing-header h2{font-size:1.8rem;font-weight:900;color:#1a1d2e}.landing-header p{color:#888;margin-top:4px;font-size:1rem}.topic-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:16px}.topic-card{background:var(--content-bg);border-radius:var(--radius-lg);padding:24px;cursor:pointer;box-shadow:var(--card-shadow);transition:all var(--transition);border:2px solid transparent;position:relative;overflow:hidden}.topic-card:before{content:"";position:absolute;top:0;left:0;width:100%;height:4px}.topic-card:hover{transform:translateY(-3px);box-shadow:var(--card-shadow-hover)}.topic-card[data-cat=math]:before{background:var(--math-color)}.topic-card[data-cat=math]:hover{border-color:var(--math-color)}.topic-card[data-cat=micro]:before{background:var(--micro-color)}.topic-card[data-cat=micro]:hover{border-color:var(--micro-color)}.topic-card[data-cat=macro]:before{background:var(--macro-color)}.topic-card[data-cat=macro]:hover{border-color:var(--macro-color)}.topic-card .tc-icon{font-size:2rem;margin-bottom:8px}.topic-card .tc-name{font-size:1.05rem;font-weight:800}.topic-card .tc-desc{font-size:.82rem;color:#999;margin-top:4px;line-height:1.4}.topic-card .tc-badge{display:inline-block;margin-top:10px;font-size:.7rem;font-weight:700;padding:3px 10px;border-radius:20px;color:#fff}.topic-card[data-cat=math] .tc-badge{background:var(--math-color)}.topic-card[data-cat=micro] .tc-badge{background:var(--micro-color)}.topic-card[data-cat=macro] .tc-badge{background:var(--macro-color)}.quiz-card{background:var(--content-bg);border-radius:var(--radius-lg);box-shadow:var(--card-shadow);padding:32px;max-width:800px;margin:0 auto;animation:slideUp .25s ease}.quiz-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:20px}.quiz-top h2{font-size:1.3rem;font-weight:800}.quiz-back-btn{background:#f0f2f5;border:none;border-radius:8px;padding:7px 14px;font-family:var(--font);font-weight:700;font-size:.85rem;cursor:pointer;transition:background var(--transition);color:#555}.quiz-back-btn:hover{background:#e4e6ea}.progress-bar{height:6px;background:#e8eaed;border-radius:3px;overflow:hidden;margin-bottom:24px}.progress-fill{height:100%;border-radius:3px;transition:width .4s ease}.question{text-align:center;font-size:2rem;font-weight:800;padding:20px 0;min-height:80px;display:flex;align-items:center;justify-content:center;gap:8px;flex-wrap:wrap}.frac{display:inline-flex;flex-direction:column;align-items:center;vertical-align:middle;margin:0 6px}.frac-num{border-bottom:2px solid #2d2d3a;padding:0 6px 2px;font-weight:800}.frac-den{padding:2px 6px 0;font-weight:800}.answer-area{display:flex;gap:12px;justify-content:center;align-items:center;flex-wrap:wrap}.answer-input{width:140px;padding:12px 16px;font-size:1.4rem;font-family:var(--font);font-weight:700;border:2px solid #e0e0e0;border-radius:10px;text-align:center;outline:none;transition:border-color var(--transition)}.answer-input:focus{border-color:var(--math-color)}.check-btn{padding:12px 24px;font-size:1rem;font-family:var(--font);font-weight:800;border:none;border-radius:10px;color:#fff;cursor:pointer;transition:transform .15s,opacity 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#3b82f6);background:#f8faff}.mc-choice.correct{border-color:#2ed573;background:#f0fff5}.mc-choice.wrong{border-color:#ff4757;background:#fff5f5}.mc-choice.disabled{cursor:default;opacity:.85}.mc-letter{width:32px;height:32px;border-radius:8px;display:flex;align-items:center;justify-content:center;font-weight:800;font-size:.85rem;background:#f0f2f5;color:#555;flex-shrink:0;transition:all var(--transition)}.mc-choice:hover:not(.disabled) .mc-letter{background:var(--accent, #3b82f6);color:#fff}.mc-choice.correct .mc-letter{background:#2ed573;color:#fff}.mc-choice.wrong .mc-letter{background:#ff4757;color:#fff}.mc-text{flex:1;line-height:1.4}.mc-feedback{margin-top:8px}.feedback-correct{color:#2ed573;font-weight:700;font-size:1rem}.feedback-wrong{color:#ff4757;font-weight:700;font-size:1rem}.mc-explanation{margin-top:10px;padding:14px 16px;background:#f8f9fb;border-radius:10px;font-size:.9rem;line-height:1.5;color:#555;border-left:3px solid #3b82f6}.fr-question{font-size:1.1rem;font-weight:700;line-height:1.6;margin-bottom:16px;color:#1a1d2e}.fr-textarea{width:100%;padding:14px 16px;font-size:.95rem;font-family:var(--font);border:2px solid #e8eaed;border-radius:12px;resize:vertical;outline:none;line-height:1.6;transition:border-color var(--transition);color:#2d2d3a}.fr-textarea:focus{border-color:#3b82f6}.fr-textarea:disabled{background:#f8f9fb;color:#888}.fr-actions{display:flex;justify-content:space-between;align-items:center;margin-top:10px;margin-bottom:12px}.fr-char-count{font-size:.8rem;color:#aaa}.fr-submit{padding:10px 22px;font-size:.9rem;font-family:var(--font);font-weight:700;border:none;border-radius:10px;color:#fff;cursor:pointer;transition:transform .15s}.fr-submit:hover{transform:scale(1.04)}.fr-feedback{border-top:1px solid #eee;padding-top:20px;margin-top:8px}.fr-rubric{margin-bottom:16px}.fr-rubric h4,.fr-sample h4{font-size:.9rem;font-weight:800;margin-bottom:8px;color:#1a1d2e}.fr-rubric ul{list-style:none;padding:0}.fr-rubric li{padding:6px 0 6px 22px;font-size:.88rem;color:#555;position:relative}.fr-rubric li:before{content:"✓";position:absolute;left:0;color:#2ed573;font-weight:700}.fr-sample{background:#f0f8ff;padding:16px;border-radius:10px;margin-bottom:16px}.fr-sample p{font-size:.88rem;line-height:1.6;color:#444}.fr-self-score{text-align:center;padding:12px 0}.fr-self-score p{font-size:.9rem;font-weight:700;color:#888;margin-bottom:10px}.fr-score-btns{display:flex;gap:10px;justify-content:center;flex-wrap:wrap}.fr-score-btn{padding:10px 18px;border:2px solid #e8eaed;border-radius:10px;background:#fff;font-family:var(--font);font-weight:700;font-size:.85rem;cursor:pointer;transition:all var(--transition);color:#555}.fr-score-btn:hover{border-color:var(--accent, #888)}.fr-score-btn.selected{border-color:var(--accent, #888);background:var(--accent, #888);color:#fff}.mode-selector{display:flex;gap:12px;margin-bottom:20px}.mode-btn{padding:10px 20px;border:2px solid 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.review-badge{color:#2ed573}.review-wrong .review-badge{color:#ff4757}.table-toggle{text-align:center;margin-top:16px}.table-toggle button{background:none;border:2px dashed #ddd;border-radius:8px;padding:6px 14px;font-family:var(--font);font-weight:600;color:#aaa;cursor:pointer;font-size:.82rem;transition:all var(--transition)}.table-toggle button:hover{border-color:#bbb;color:#777}.mult-table{display:none;margin-top:12px;font-size:.82rem;background:#fafbfc;border-radius:10px;padding:12px;overflow-x:auto}.mult-table table{border-collapse:collapse;width:100%}.mult-table th,.mult-table td{padding:5px 7px;text-align:center;border:1px solid #eee}.mult-table th{background:#f0f2f5;font-weight:700}.mult-table .highlight{background:#fff3cd;font-weight:700}@keyframes shake{0%,to{transform:translate(0)}20%,60%{transform:translate(-6px)}40%,80%{transform:translate(6px)}}@keyframes pop{0%{transform:scale(.85);opacity:0}60%{transform:scale(1.03)}to{transform:scale(1);opacity:1}}@keyframes slideUp{0%{opacity:0;transform:translateY(12px)}to{opacity:1;transform:translateY(0)}}.shake{animation:shake .35s ease}.pop{animation:pop .3s ease}.confetti-container{position:fixed;top:0;left:0;width:100%;height:100%;pointer-events:none;overflow:hidden;z-index:200}.confetti-piece{position:absolute;border-radius:2px;animation:confetti-fall 3s ease-out forwards}@keyframes confetti-fall{0%{transform:translateY(-20px) rotate(0);opacity:1}to{transform:translateY(100vh) rotate(720deg);opacity:0}}@media (max-width: 768px){.sidebar{transform:translate(-100%)}.sidebar.open{transform:translate(0)}.sidebar-overlay.show{display:block}.hamburger{display:flex;align-items:center;justify-content:center}.main{margin-left:0;padding:64px 20px 20px}.topic-grid{grid-template-columns:1fr}.question{font-size:1.5rem}.answer-input{width:110px;font-size:1.2rem}.quiz-card{padding:20px}}