.vocabulary{max-width:900px;margin:0 auto;padding:2rem}.vocabulary-header{text-align:center;margin-bottom:2rem}.vocabulary-header h1{font-size:2.5rem;color:#2d3748;margin-bottom:.5rem}.vocabulary-subtitle{color:#718096;font-size:1.1rem}.vocabulary-controls{display:flex;gap:1rem;margin-bottom:2rem;flex-wrap:wrap}.search-box{flex:1;min-width:200px}.search-input{width:100%;padding:.75rem 1rem;border:2px solid #e2e8f0;border-radius:8px;font-size:1rem;transition:border-color .2s}.search-input:focus{outline:none;border-color:#667eea}.topic-filter{display:flex;align-items:center;gap:.5rem}.topic-filter label{color:#4a5568;font-weight:500;white-space:nowrap}.topic-select{padding:.75rem 1rem;border:2px solid #e2e8f0;border-radius:8px;font-size:1rem;background:#fff;cursor:pointer;min-width:200px}.topic-select:focus{outline:none;border-color:#667eea}.vocabulary-stats{display:flex;gap:2rem;margin-bottom:2rem;padding:1rem;background:#f7fafc;border-radius:8px;flex-wrap:wrap}.stat{display:flex;gap:.5rem}.stat-label{color:#718096;font-weight:500}.stat-value{color:#2d3748;font-weight:600}.vocabulary-progress{margin-bottom:2rem}.progress-bar{width:100%;height:10px;background:#e2e8f0;border-radius:5px;overflow:hidden;margin-bottom:.5rem}.progress-fill{height:100%;background:linear-gradient(90deg,#667eea,#764ba2);transition:width .3s ease}.progress-text{text-align:center;color:#718096;font-size:.9rem}.vocabulary-card-container{perspective:1000px;margin-bottom:2rem;min-height:300px}.vocabulary-card{width:100%;height:300px;position:relative;transform-style:preserve-3d;transition:transform .6s;cursor:pointer}.vocabulary-card.flipped{transform:rotateY(180deg)}.vocabulary-card-front,.vocabulary-card-back{position:absolute;width:100%;height:100%;backface-visibility:hidden;border-radius:16px;box-shadow:0 4px 6px #0000001a;display:flex;align-items:center;justify-content:center}.vocabulary-card-front{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff}.vocabulary-card-back{background:#fff;color:#2d3748;transform:rotateY(180deg);border:2px solid #e2e8f0}.card-content{padding:2rem;text-align:center;width:100%}.card-topic{font-size:.875rem;opacity:.8;margin-bottom:1rem;font-weight:500}.card-term{font-size:2rem;font-weight:700;margin:1rem 0;line-height:1.3}.card-definition{font-size:1.25rem;line-height:1.6;color:#4a5568}.card-hint{margin-top:2rem;font-size:.875rem;opacity:.7;font-style:italic}.vocabulary-controls-bottom{display:flex;justify-content:center;gap:1rem;margin-top:2rem}.btn{padding:.75rem 1.5rem;border:none;border-radius:8px;font-size:1rem;font-weight:600;cursor:pointer;transition:all .2s}.btn-primary{background:linear-gradient(135deg,#667eea,#764ba2);color:#fff}.btn-primary:hover:not(:disabled){transform:translateY(-2px);box-shadow:0 4px 12px #667eea66}.btn-secondary{background:#f7fafc;color:#4a5568;border:2px solid #e2e8f0}.btn-secondary:hover:not(:disabled){background:#edf2f7;border-color:#cbd5e0}.btn:disabled{opacity:.5;cursor:not-allowed}.loading,.no-results{text-align:center;padding:3rem;color:#718096;font-size:1.1rem}@media(max-width:768px){.vocabulary{padding:1rem}.vocabulary-controls{flex-direction:column}.topic-select{width:100%}.vocabulary-stats{flex-direction:column;gap:.5rem}.card-term{font-size:1.5rem}.card-definition{font-size:1rem}}