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ease}.progress-text{position:absolute;right:0;top:-25px;font-size:.9rem;color:#666;font-weight:500}.flashcard{width:100%;height:400px;perspective:1000px;cursor:pointer;margin-bottom:2rem}.flashcard-inner{position:relative;width:100%;height:100%;transition:transform .6s;transform-style:preserve-3d}.flashcard.flipped .flashcard-inner{transform:rotateY(180deg)}.flashcard-front,.flashcard-back{position:absolute;width:100%;height:100%;backface-visibility:hidden;border-radius:16px;box-shadow:0 8px 24px #0000001f;padding:2rem;display:flex;flex-direction:column;background:#fff;border:1px solid #e0e0e0;overflow:hidden}.flashcard-back{transform:rotateY(180deg);background:linear-gradient(135deg,#f8f9fa,#fff)}.card-meta{display:flex;justify-content:space-between;align-items:center;margin-bottom:2rem;gap:1rem}.topic-badge{background:#e3f2fd;color:#1976d2;padding:.4rem 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#00000026}.quality-btn:active{transform:translateY(-1px)}.btn-label{font-size:1.1rem}.btn-subtitle{font-size:.75rem;font-weight:400;opacity:.85}.btn-keyboard{position:absolute;top:.5rem;right:.5rem;background:#ffffff4d;color:inherit;width:24px;height:24px;border-radius:4px;display:flex;align-items:center;justify-content:center;font-size:.75rem;font-weight:600}.quality-btn.fail{background:#ffebee;color:#c62828}.quality-btn.fail:hover{background:#ffcdd2}.quality-btn.hard{background:#fff3e0;color:#e65100}.quality-btn.hard:hover{background:#ffe0b2}.quality-btn.good{background:#e8f5e9;color:#2e7d32}.quality-btn.good:hover{background:#c8e6c9}.quality-btn.easy{background:#e3f2fd;color:#1565c0}.quality-btn.easy:hover{background:#bbdefb}.study-tip{text-align:center;padding:1rem;background:#f8f9fa;border-radius:8px;color:#666;font-size:.9rem;animation:fadeIn .3s ease}.study-tip p{margin:0}.loading-spinner,.no-cards{text-align:center;padding:4rem 2rem}.no-cards h2{font-size:2rem;margin-bottom:1rem;color:#333}.no-cards p{font-size:1.1rem;color:#666;margin-bottom:2rem}.completion-modal-overlay{position:fixed;inset:0;background:#0009;display:flex;align-items:center;justify-content:center;z-index:1000;padding:1rem;animation:fadeIn .3s ease}.completion-modal{background:#fff;border-radius:20px;padding:3rem;max-width:600px;width:100%;box-shadow:0 12px 48px #0000004d;animation:slideUp .4s ease}@keyframes slideUp{0%{opacity:0;transform:translateY(40px)}to{opacity:1;transform:translateY(0)}}.completion-modal h2{text-align:center;font-size:2rem;margin:0 0 2rem;color:#333}.completion-stats{display:grid;grid-template-columns:repeat(2,1fr);gap:1.5rem;margin-bottom:2.5rem}.completion-stats .stat{text-align:center;padding:1.5rem;background:linear-gradient(135deg,#f8f9fa,#fff);border-radius:12px;box-shadow:0 2px 8px #00000014}.completion-stats .stat-value{display:block;font-size:2.5rem;font-weight:700;margin-bottom:.5rem;color:#1976d2}.completion-stats .stat-label{display:block;font-size:.9rem;color:#666;font-weight:500}.completion-actions{display:flex;gap:1rem;flex-direction:column}.completion-actions .btn-primary,.completion-actions .btn-secondary{width:100%;padding:1rem 2rem;font-size:1.1rem;border:none;border-radius:12px;font-weight:600;cursor:pointer;transition:all .2s ease;box-shadow:0 2px 8px #0000001a}.completion-actions .btn-primary{background:linear-gradient(135deg,#1976d2,#2196f3);color:#fff}.completion-actions .btn-primary:hover:not(:disabled){background:linear-gradient(135deg,#1565c0,#1976d2);transform:translateY(-2px);box-shadow:0 4px 16px #1976d24d}.completion-actions .btn-secondary{background:#fff;color:#666;border:2px solid #e0e0e0}.completion-actions .btn-secondary:hover:not(:disabled){background:#f8f9fa;border-color:#bdbdbd;transform:translateY(-2px);box-shadow:0 4px 16px #00000026}.completion-actions .btn-primary:disabled,.completion-actions .btn-secondary:disabled{opacity:.6;cursor:not-allowed}@media(max-width:768px){.flashcard-study-container{padding:1rem .5rem}.study-header{flex-direction:column;align-items:flex-start}.stats-summary{width:100%;justify-content:space-around}.flashcard{height:350px}.flashcard-front,.flashcard-back{padding:1.5rem}.card-content{font-size:1.1rem}.quality-buttons{grid-template-columns:repeat(2,1fr);gap:.75rem}.quality-btn{padding:1rem .75rem}.btn-label{font-size:1rem}.btn-subtitle{font-size:.7rem}.completion-modal{padding:2rem 1.5rem}.completion-modal h2{font-size:1.5rem}.completion-stats{gap:1rem}.completion-stats .stat{padding:1rem}.completion-stats .stat-value{font-size:2rem}}@media(max-width:480px){.flashcard{height:320px}.study-header h2{font-size:1.2rem}.card-content{font-size:1rem}.completion-stats{grid-template-columns:1fr;gap:.75rem}.completion-modal{padding:1.5rem 1rem}.completion-modal h2{font-size:1.3rem;margin-bottom:1.5rem}.completion-stats .stat-value{font-size:1.8rem}.completion-actions .btn-primary,.completion-actions .btn-secondary{padding:.9rem 1.5rem;font-size:1rem}}