:root{--bg-primary: #0d1117;--bg-surface: #161b22;--bg-card: #21262d;--bg-card-hover: #2d333b;--accent: #f97316;--accent-light: #fb923c;--accent-dark: #c2410c;--accent-muted: #431407;--text-primary: #f0f6fc;--text-secondary: #b0bec5;--text-muted: #6e7681;--border: #30363d;--border-accent: #f97316;--success-bg: #0f2d16;--success-border: #238636;--success-text: #56d364;--error-bg: #2d0a0a;--error-border: #da3633;--error-text: #f85149;--warning: #d29922;--srs-again: #da3633;--srs-hard: #d29922;--srs-good: #238636;--srs-easy: #1f6feb}*{margin:0;padding:0;box-sizing:border-box}html{font-size:18px}body{font-family:Segoe UI,Tahoma,Geneva,Verdana,sans-serif;background:var(--bg-primary);min-height:100vh;color:var(--text-primary);line-height:1.7}.app{min-height:100vh;padding:20px}.container{max-width:1400px;margin:0 auto}.header{text-align:center;padding:40px 20px;background:linear-gradient(135deg,var(--accent-dark) 0%,var(--accent) 100%);border-radius:16px;margin-bottom:30px;box-shadow:0 8px 32px #00000080;border:2px solid var(--accent-light)}.header h1{font-size:2.6rem;color:#fff;margin-bottom:10px;text-shadow:2px 2px 6px rgba(0,0,0,.4);font-weight:800}.header p{font-size:1.15rem;color:#ffe0cc;font-style:italic}.mode-selector{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:20px;margin-bottom:30px}.mode-card{background:var(--bg-card);padding:30px;border-radius:16px;cursor:pointer;transition:all .25s ease;border:2px solid var(--border);box-shadow:0 4px 16px #0006}.mode-card:hover{transform:translateY(-6px);border-color:var(--accent);box-shadow:0 8px 28px #f973164d;background:var(--bg-card-hover)}.mode-icon{font-size:3rem;margin-bottom:14px;text-align:center}.mode-card h3{font-size:1.4rem;margin-bottom:8px;color:var(--accent-light);text-align:center}.mode-card p{color:var(--text-secondary);text-align:center;font-size:1rem;line-height:1.5}.mode-card .due-badge{display:inline-block;background:var(--srs-again);color:#fff;font-size:.8rem;padding:2px 10px;border-radius:12px;margin-top:8px;font-weight:700}.content-area{background:var(--bg-surface);padding:30px;border-radius:16px;box-shadow:0 8px 32px #00000080;border:2px solid var(--border);animation:fadeIn .4s ease}.btn{padding:12px 26px;border:none;border-radius:10px;font-size:1rem;cursor:pointer;transition:all .2s ease;font-weight:700;box-shadow:0 2px 8px #0000004d;letter-spacing:.02em}.btn-primary{background:linear-gradient(135deg,var(--accent) 0%,var(--accent-dark) 100%);color:#fff}.btn-primary:hover{transform:translateY(-2px);box-shadow:0 4px 18px #f9731680}.btn-secondary{background:var(--bg-card);color:var(--text-primary);border:2px solid var(--border)}.btn-secondary:hover{border-color:var(--accent);color:var(--accent-light);transform:translateY(-2px)}.btn-danger{background:linear-gradient(135deg,#da3633,#9b1c1c);color:#fff}.btn-danger:hover{transform:translateY(-2px);box-shadow:0 4px 16px #da363366}.btn:disabled{opacity:.4;cursor:not-allowed;transform:none!important}.controls{display:flex;justify-content:center;gap:14px;flex-wrap:wrap;margin-top:20px}.srs-buttons{display:flex;justify-content:center;gap:12px;flex-wrap:wrap;margin-top:20px}.srs-btn{padding:14px 22px;border:none;border-radius:10px;font-size:.95rem;font-weight:700;cursor:pointer;transition:all .2s ease;display:flex;flex-direction:column;align-items:center;gap:2px;min-width:80px;box-shadow:0 2px 8px #0000004d}.srs-btn .srs-label{font-size:1rem}.srs-btn .srs-interval{font-size:.75rem;opacity:.85}.srs-btn-again{background:var(--srs-again);color:#fff}.srs-btn-again:hover{transform:translateY(-2px);box-shadow:0 4px 14px #da363380}.srs-btn-hard{background:var(--srs-hard);color:#fff}.srs-btn-hard:hover{transform:translateY(-2px);box-shadow:0 4px 14px #d2992280}.srs-btn-good{background:var(--srs-good);color:#fff}.srs-btn-good:hover{transform:translateY(-2px);box-shadow:0 4px 14px #23863680}.srs-btn-easy{background:var(--srs-easy);color:#fff}.srs-btn-easy:hover{transform:translateY(-2px);box-shadow:0 4px 14px #1f6feb80}.srs-hint{text-align:center;font-size:.9rem;color:var(--text-muted);margin-top:8px}.progress-bar{width:100%;height:12px;background:var(--bg-card);border-radius:10px;overflow:hidden;margin-bottom:20px;border:1px solid var(--border)}.progress-fill{height:100%;background:linear-gradient(90deg,var(--accent) 0%,var(--accent-dark) 100%);transition:width .5s ease;border-radius:10px}.flashcard{perspective:1000px;margin:24px auto;max-width:720px;min-height:460px}.flashcard-inner{position:relative;width:100%;min-height:460px;text-align:center;transition:transform .55s;transform-style:preserve-3d;cursor:pointer}.flashcard-inner.flipped{transform:rotateY(180deg)}.flashcard-front,.flashcard-back{position:absolute;width:100%;min-height:460px;backface-visibility:hidden;border-radius:16px;padding:40px;display:flex;flex-direction:column;justify-content:center;box-shadow:0 8px 32px #00000080;border:2px solid var(--border-accent)}.flashcard-front{background:var(--bg-card);color:var(--text-primary)}.flashcard-back{background:linear-gradient(145deg,#1a1a2e,#16213e);color:var(--text-primary);transform:rotateY(180deg);overflow-y:auto;border-color:var(--accent-light)}.flashcard-hint{position:absolute;bottom:18px;left:0;right:0;font-size:.9rem;color:var(--text-muted);font-style:italic;text-align:center}.srs-status-chip{position:absolute;top:16px;right:16px;padding:4px 12px;border-radius:12px;font-size:.78rem;font-weight:700;letter-spacing:.04em}.srs-new{background:#1f3a6e;color:#58a6ff;border:1px solid #1f6feb}.srs-due{background:#3d1f00;color:#f97316;border:1px solid #f97316}.srs-review{background:#0f2d16;color:#56d364;border:1px solid #238636}.artCultureData-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(340px,1fr));gap:20px;margin-top:20px}.topic-card{background:var(--bg-card);padding:24px;border-radius:12px;border:2px solid var(--border);box-shadow:0 4px 12px #0000004d;transition:all .25s ease}.topic-card:hover{transform:translateY(-4px);border-color:var(--accent);box-shadow:0 6px 22px #f9731640}.topic-card h3{color:var(--accent-light);font-size:1.25rem;margin-bottom:10px}.topic-info{font-size:1.05rem;line-height:1.8;margin:6px 0;color:var(--text-secondary)}.topic-info strong{color:var(--accent-light)}.tags{display:flex;gap:8px;flex-wrap:wrap;margin-top:12px}.tag{display:inline-block;padding:5px 14px;background:var(--accent-muted);border-radius:16px;font-size:.85rem;color:var(--accent-light);border:1px solid var(--accent);font-weight:600}.tag.high{background:#2d1f00;border-color:var(--warning);color:var(--warning)}.quiz-question{background:var(--bg-card);padding:30px;border-radius:16px;margin-top:20px;border:2px solid var(--border);box-shadow:0 4px 16px #0000004d}.quiz-question h3{color:var(--text-muted);margin-bottom:16px;font-size:1.1rem}.quiz-question p{font-size:1.25rem;color:var(--text-primary);line-height:1.7}.quiz-options{display:flex;flex-direction:column;gap:14px;margin-top:22px}.quiz-option{padding:18px 24px;background:var(--bg-surface);border:2px solid var(--border);border-radius:12px;cursor:pointer;transition:all .25s ease;font-size:1.1rem;text-align:left;color:var(--text-primary);line-height:1.6}.quiz-option:hover{background:var(--bg-card-hover);border-color:var(--accent);transform:translate(5px)}.quiz-option.correct{background:var(--success-bg);border-color:var(--success-border);color:var(--success-text);font-weight:700}.quiz-option.incorrect{background:var(--error-bg);border-color:var(--error-border);color:var(--error-text);font-weight:700}.result-screen{text-align:center;padding:40px}.result-emoji{font-size:5rem;margin-bottom:20px;animation:bounce 1s ease infinite}@keyframes bounce{0%,to{transform:translateY(0)}50%{transform:translateY(-18px)}}.result-score{font-size:4rem;color:var(--accent-light);font-weight:800;margin:20px 0}.filter-section{margin-bottom:20px;padding:16px;background:var(--bg-card);border-radius:12px;border:2px solid var(--border)}.filter-section h3{font-size:1.1rem;color:var(--text-secondary);margin-bottom:10px}.filter-buttons{display:flex;gap:10px;flex-wrap:wrap;margin-top:10px}.filter-btn{padding:10px 18px;border:2px solid var(--border);background:var(--bg-surface);border-radius:20px;cursor:pointer;transition:all .25s ease;font-size:.95rem;color:var(--text-secondary);font-weight:600}.filter-btn:hover{border-color:var(--accent);color:var(--accent-light);transform:translateY(-2px)}.filter-btn.active{background:var(--accent);color:#fff;border-color:var(--accent-dark)}.stats{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:20px;margin-bottom:30px}.stat-card{background:var(--bg-card);padding:24px;border-radius:12px;text-align:center;border:2px solid var(--border);box-shadow:0 4px 12px #0000004d;transition:all .25s ease}.stat-card:hover{transform:translateY(-4px);border-color:var(--accent);box-shadow:0 6px 20px #f9731633}.stat-card h4{color:var(--text-secondary);font-size:1rem;margin-bottom:12px;text-transform:uppercase;letter-spacing:.05em}.stat-card .value{font-size:2.6rem;font-weight:800;color:var(--accent-light)}.srs-stats{display:flex;gap:10px;flex-wrap:wrap;justify-content:center;margin:16px 0}.srs-stat-chip{padding:8px 16px;border-radius:20px;font-size:.9rem;font-weight:700}.srs-chip-new{background:#1f3a6e;color:#58a6ff;border:1px solid #1f6feb}.srs-chip-due{background:#3d1f00;color:#f97316;border:1px solid #f97316}.srs-chip-review{background:#0f2d16;color:#56d364;border:1px solid #238636}.srs-chip-total{background:var(--bg-card);color:var(--text-secondary);border:1px solid var(--border)}.navigator-overlay{position:fixed;inset:0;background:#000000bf;display:flex;justify-content:center;align-items:center;z-index:1000;padding:20px}.navigator-box{background:var(--bg-surface);border-radius:16px;padding:30px;max-width:700px;max-height:80vh;overflow:auto;width:100%;box-shadow:0 10px 40px #0009;border:2px solid var(--border)}.navigator-box h3{font-size:1.3rem;color:var(--text-primary)}::-webkit-scrollbar{width:10px}::-webkit-scrollbar-track{background:var(--bg-surface);border-radius:10px}::-webkit-scrollbar-thumb{background:var(--accent-dark);border-radius:10px;border:2px solid var(--bg-surface)}::-webkit-scrollbar-thumb:hover{background:var(--accent)}.flashcard-back strong{font-size:1.1rem;color:var(--accent-light)}.flashcard-back ul{font-size:1.05rem;line-height:1.75;color:var(--text-secondary)}.answer-feedback{margin-top:20px;padding:20px;border-radius:12px;border:2px solid}.answer-feedback.correct{background:var(--success-bg);border-color:var(--success-border);color:var(--success-text)}.answer-feedback.incorrect{background:var(--error-bg);border-color:var(--error-border);color:var(--error-text)}.answer-feedback p{font-size:1.05rem;line-height:1.6}.answer-feedback .explanation{color:var(--text-secondary);margin-top:8px}.flashcard-back .section-divider{border-top:1px solid #2d333b;margin:10px 0 6px;padding-top:8px}.card-counter{text-align:center;margin-top:16px;color:var(--text-muted);font-size:1rem}@keyframes fadeIn{0%{opacity:0;transform:translateY(16px)}to{opacity:1;transform:translateY(0)}}@media(max-width:768px){html{font-size:16px}.header h1{font-size:2rem}.mode-selector,.artCultureData-grid{grid-template-columns:1fr}.flashcard-front,.flashcard-back{min-height:420px;padding:28px 18px}.controls{flex-direction:column}.btn{width:100%}.srs-buttons{gap:8px}.srs-btn{min-width:70px;padding:12px 14px}}