.header{background:rgba(255,255,255,.95);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-bottom:1px solid var(--border-color);position:sticky;top:0;z-index:100;padding:0 20px;box-shadow:0 4px 16px var(--shadow-color);transition:all .3s ease}[data-theme=dark] .header{background:rgba(30,41,59,.95)}.header-content{max-width:1200px;margin:0 auto;display:flex;align-items:center;justify-content:space-between;height:64px}.header-left .logo{font-size:22px;font-weight:800;background:var(--gradient-primary);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;text-decoration:none;display:flex;align-items:center;gap:8px;transition:transform .2s ease}.header-left .logo:hover{transform:scale(1.02)}.header-right{display:flex;align-items:center;gap:16px}.back-button{color:var(--text-secondary);text-decoration:none;font-size:14px;font-weight:600;padding:10px 16px;border-radius:10px;transition:all .2s;display:flex;align-items:center;gap:6px;background:rgba(107,114,128,.1)}.back-button:hover{color:var(--text-primary);background:rgba(107,114,128,.15);transform:translateY(-1px)}.more-menu{position:relative}.more-button{background:rgba(107,114,128,.1);border:none;color:var(--text-secondary);cursor:pointer;padding:10px;border-radius:10px;transition:all .2s;line-height:1;display:flex;align-items:center;justify-content:center}.more-button:hover{background:rgba(107,114,128,.15);color:var(--text-primary);transform:translateY(-1px)}.menu-overlay{position:fixed;top:0;left:0;right:0;bottom:0;background:transparent;z-index:200}.dropdown-menu{position:absolute;top:100%;right:0;background:var(--bg-secondary);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid var(--border-color);border-radius:12px;box-shadow:0 16px 40px var(--shadow-color);min-width:200px;padding:8px 0;z-index:300;margin-top:8px}.menu-item{width:100%;padding:12px 20px;background:none;border:none;text-align:left;font-size:14px;font-weight:600;color:var(--text-primary);cursor:pointer;transition:all .2s;display:flex;align-items:center;gap:12px}.menu-item:hover{background:rgba(59,130,246,.1);color:var(--text-primary)}.menu-item.danger{color:#dc2626}.menu-item.danger:hover{background:rgba(220,38,38,.1);color:#b91c1c}.menu-divider{margin:8px 0;border:none;border-top:1px solid var(--border-color)}@media (max-width: 640px){.header{padding:0 16px}.header-content{height:56px}.header-left .logo{font-size:18px}.back-button{font-size:13px;padding:6px 10px}.dropdown-menu{min-width:160px;right:-8px}}.home{min-height:calc(100vh - 64px);padding:40px 20px;background:var(--gradient-primary);background-attachment:fixed;transition:background .3s ease}.home-container{max-width:1000px;margin:0 auto}.hero{text-align:center;margin-bottom:60px;padding:60px 20px;background:var(--bg-secondary);border-radius:24px;box-shadow:0 20px 40px var(--shadow-color);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid var(--border-color);transition:all .3s ease}.hero-title{font-size:56px;font-weight:800;background:var(--gradient-primary);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;margin-bottom:20px;line-height:1.1}.hero-subtitle{font-size:22px;color:var(--text-secondary);margin-bottom:32px;line-height:1.4;max-width:500px;margin-left:auto;margin-right:auto;font-weight:600}.hero-steps{display:flex;justify-content:center;gap:40px;margin-bottom:40px;flex-wrap:wrap}.step{display:flex;align-items:center;gap:12px;color:var(--text-primary)}.step-number{background:var(--gradient-primary);color:#fff;width:32px;height:32px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:14px;font-weight:700;box-shadow:0 4px 12px #667eea4d}.step-text{font-size:16px;font-weight:600;color:var(--text-primary)}.study-now-button{background:linear-gradient(135deg,#667eea 0%,#764ba2 100%);color:#fff;border:none;border-radius:16px;padding:18px 36px;font-size:20px;font-weight:700;cursor:pointer;transition:all .3s ease;box-shadow:0 8px 24px #667eea66;margin-bottom:24px;display:inline-flex;align-items:center;gap:12px;transform:translateY(0)}.study-now-button:hover{transform:translateY(-3px);box-shadow:0 12px 32px #667eea80}.study-now-button:active{transform:translateY(-1px)}.button-icon{transition:transform .3s ease}.study-now-button:hover .button-icon{transform:scale(1.1)}.create-deck-link{color:#667eea;text-decoration:none;font-size:16px;font-weight:600;display:inline-flex;align-items:center;gap:8px;margin-top:16px;padding:12px 20px;border-radius:12px;transition:all .2s;background:rgba(102,126,234,.1)}.create-deck-link:hover{background:rgba(102,126,234,.15);transform:translateY(-1px)}.deck-section{margin-top:40px}.section-title{font-size:28px;font-weight:700;color:#fff;margin-bottom:32px;text-align:center;text-shadow:0 2px 4px rgba(0,0,0,.3)}.deck-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(350px,1fr));gap:24px}.deck-card{background:var(--bg-secondary);border-radius:20px;padding:24px;border:1px solid var(--border-color);box-shadow:0 8px 32px var(--shadow-color);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);transition:all .3s ease;display:flex;justify-content:space-between;align-items:flex-start;position:relative;overflow:hidden}.deck-card:before{content:"";position:absolute;top:0;left:0;right:0;height:4px;background:var(--gradient-primary);opacity:0;transition:opacity .3s ease}.deck-card:hover{transform:translateY(-4px);box-shadow:0 16px 48px var(--shadow-color)}.deck-card:hover:before{opacity:1}.deck-card.is-default{border-color:#667eea;background:linear-gradient(135deg,rgba(102,126,234,.05) 0%,rgba(118,75,162,.05) 100%)}.deck-card.is-default:before{opacity:1}.deck-content{flex:1}.deck-header{display:flex;align-items:center;gap:8px;margin-bottom:12px}.deck-name{font-size:20px;font-weight:700;color:var(--text-primary);margin:0}.default-icon{color:#f59e0b;flex-shrink:0}.deck-description{font-size:14px;color:var(--text-secondary);margin-bottom:16px;line-height:1.5;font-weight:500}.deck-meta{display:flex;align-items:center;gap:12px}.deck-stats{font-size:14px;color:var(--text-secondary);font-weight:500}.default-badge{display:inline-block;background:var(--gradient-primary);color:#fff;font-size:11px;font-weight:700;padding:4px 10px;border-radius:12px;text-transform:uppercase;letter-spacing:.5px}.start-now-button{background:linear-gradient(135deg,#10b981 0%,#059669 100%);color:#fff;border:none;padding:12px 20px;border-radius:12px;font-size:14px;font-weight:700;cursor:pointer;transition:all .3s ease;margin-top:16px;width:100%;display:flex;align-items:center;justify-content:center;gap:8px;box-shadow:0 4px 16px #10b9814d}.start-now-button:hover{transform:translateY(-2px);box-shadow:0 8px 24px #10b98166;background:linear-gradient(135deg,#059669 0%,#047857 100%)}.start-now-button:active{transform:translateY(0)}.deck-actions{display:flex;gap:8px;flex-shrink:0}.action-button{background:rgba(107,114,128,.1);border:none;padding:10px;border-radius:12px;cursor:pointer;transition:all .2s ease;color:#6b7280;display:flex;align-items:center;justify-content:center}.action-button:hover{transform:translateY(-1px);box-shadow:0 4px 12px #00000026}.edit-button:hover{background:rgba(59,130,246,.1);color:#3b82f6}.delete-button:hover{background:rgba(239,68,68,.1);color:#ef4444}.empty-state{text-align:center;padding:80px 20px;background:rgba(255,255,255,.95);border-radius:24px;box-shadow:0 20px 40px #0000001a;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}.empty-icon{font-size:80px;margin-bottom:24px}.empty-state h3{font-size:24px;font-weight:700;color:#374151;margin-bottom:12px}.empty-state p{font-size:16px;color:#6b7280;margin:0}@media (max-width: 768px){.home{padding:20px 16px}.hero{padding:40px 20px}.hero-title{font-size:42px}.hero-subtitle{font-size:18px}.study-now-button{width:100%;font-size:18px;justify-content:center}.deck-grid{grid-template-columns:1fr}.deck-card{flex-direction:column;gap:20px}.deck-actions{align-self:flex-end}}.study{min-height:calc(100vh - 64px);background:var(--gradient-primary);display:flex;flex-direction:column;padding:20px;transition:background .3s ease}.study-container{max-width:600px;margin:0 auto;flex:1;display:flex;flex-direction:column;justify-content:center}.study-header{text-align:center;margin-bottom:40px;background:var(--bg-secondary);padding:24px;border-radius:20px;box-shadow:0 8px 32px var(--shadow-color);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid var(--border-color)}.deck-title{color:var(--text-primary);font-size:24px;font-weight:700;margin-bottom:20px;background:var(--gradient-primary);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.progress-bar{background:var(--bg-tertiary);border-radius:12px;height:8px;overflow:hidden;margin-bottom:12px;border:1px solid var(--border-color)}.progress-fill{background:var(--gradient-primary);height:100%;transition:width .3s ease;border-radius:12px}.progress-text{color:var(--text-secondary);font-size:14px;font-weight:600}.card-container{perspective:1000px;margin-bottom:40px}.flashcard{width:100%;height:300px;position:relative;transform-style:preserve-3d;transition:transform .6s;cursor:pointer}.flashcard.flipped{transform:rotateY(180deg)}.card-face{position:absolute;width:100%;height:100%;backface-visibility:hidden;background:var(--bg-secondary);border-radius:20px;box-shadow:0 12px 40px var(--shadow-color);display:flex;align-items:center;justify-content:center;padding:40px;text-align:center;border:1px solid var(--border-color);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}.card-back{transform:rotateY(180deg);background:var(--bg-tertiary)}.card-text{font-size:20px;font-weight:600;color:var(--text-primary);line-height:1.4;word-wrap:break-word}.study-controls{display:flex;gap:20px;justify-content:center;margin-bottom:24px;max-width:400px;margin-left:auto;margin-right:auto;background:var(--bg-secondary);padding:20px;border-radius:20px;box-shadow:0 8px 32px var(--shadow-color);border:1px solid var(--border-color)}.control-button{background:var(--bg-secondary);border:1px solid var(--border-color);border-radius:16px;padding:16px 28px;font-size:16px;font-weight:700;cursor:pointer;transition:all .3s ease;box-shadow:0 4px 16px var(--shadow-color);min-width:140px;display:flex;align-items:center;justify-content:center;gap:8px;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);position:relative;overflow:hidden;color:var(--text-primary)}.control-button:before{content:"";position:absolute;top:0;left:-100%;width:100%;height:100%;background:linear-gradient(90deg,transparent,rgba(102,126,234,.2),transparent);transition:left .6s ease}.control-button:hover:before{left:100%}.control-button:hover{transform:translateY(-3px);box-shadow:0 12px 32px var(--shadow-color);border-color:var(--text-accent)}.control-button:active{transform:translateY(-1px)}.control-button.again{background:linear-gradient(135deg,rgba(239,68,68,.1) 0%,rgba(220,38,38,.1) 100%);color:#dc2626;border:2px solid rgba(239,68,68,.3)}.control-button.again:hover{background:linear-gradient(135deg,rgba(239,68,68,.2) 0%,rgba(220,38,38,.2) 100%);border-color:#ef4444;box-shadow:0 8px 24px #ef44444d}.control-button.correct{background:linear-gradient(135deg,rgba(34,197,94,.1) 0%,rgba(22,163,74,.1) 100%);color:#059669;border:2px solid rgba(34,197,94,.3)}.control-button.correct:hover{background:linear-gradient(135deg,rgba(34,197,94,.2) 0%,rgba(22,163,74,.2) 100%);border-color:#22c55e;box-shadow:0 8px 24px #22c55e4d}.control-button.flip{background:var(--gradient-primary);color:#fff;border:2px solid transparent}.control-button.flip:hover{filter:brightness(1.1);border-color:#ffffff4d;box-shadow:0 8px 24px #667eea66}.control-button:disabled{opacity:.4;cursor:not-allowed;transform:none;box-shadow:0 4px 12px #0000001a}.control-button:disabled:before{display:none}.keyboard-hint{font-size:12px;opacity:.7;font-weight:500}.keyboard-hints{text-align:center;margin-top:20px}.hint-text{color:var(--text-secondary);font-size:14px;margin-bottom:8px}.hint-keys{display:flex;gap:12px;justify-content:center;flex-wrap:wrap}.key-hint{background:var(--bg-tertiary);border:1px solid var(--border-color);border-radius:6px;padding:4px 8px;font-size:12px;color:var(--text-secondary);font-family:monospace}.session-complete{text-align:center;background:var(--bg-secondary);border:1px solid var(--border-color);border-radius:20px;padding:40px;box-shadow:0 12px 40px var(--shadow-color);max-width:500px;margin:0 auto}.complete-icon{font-size:64px;margin-bottom:24px}.complete-title{font-size:28px;font-weight:700;color:var(--text-primary);margin-bottom:16px}.complete-stats{margin-bottom:32px;display:flex;gap:2rem;justify-content:center}.stat-item{background:var(--bg-tertiary);border-radius:12px;padding:1rem;border:1px solid var(--border-color);min-width:100px}.stat-item>div:first-child{font-size:24px;font-weight:700;color:var(--text-accent);margin-bottom:4px}.stat-item>div:last-child{font-size:14px;color:var(--text-secondary)}.stat-value{font-weight:600;color:var(--text-accent)}.complete-actions{display:flex;gap:16px;justify-content:center;flex-wrap:wrap;margin-top:32px}.action-button{background:linear-gradient(135deg,#667eea 0%,#764ba2 100%);color:#fff;border:none;border-radius:12px;padding:14px 28px;font-size:16px;font-weight:700;cursor:pointer;transition:all .3s ease;text-decoration:none;display:inline-flex;align-items:center;gap:8px;box-shadow:0 8px 24px #667eea4d;position:relative;overflow:hidden}.action-button:hover{transform:translateY(-2px);box-shadow:0 12px 32px #667eea66}.action-button.secondary{background:linear-gradient(135deg,#6b7280 0%,#4b5563 100%);box-shadow:0 8px 24px #6b72804d}.action-button.secondary:hover{box-shadow:0 12px 32px #6b728066}@media (max-width: 640px){.study{padding:16px}.study-container{max-width:100%}.flashcard{height:250px}.card-face{padding:24px}.card-text{font-size:18px}.study-controls{flex-direction:column;gap:12px}.control-button{width:100%}.complete-actions{flex-direction:column}.action-button{width:100%}.hint-keys{display:none}}.create-deck{min-height:calc(100vh - 64px);background:var(--gradient-primary);background-attachment:fixed;padding:20px;transition:background .3s ease}.create-container{max-width:900px;margin:0 auto}.create-header{text-align:center;margin-bottom:40px;padding:40px 20px;background:var(--bg-secondary);border-radius:24px;box-shadow:0 20px 40px var(--shadow-color);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid var(--border-color)}.create-title{font-size:36px;font-weight:800;background:var(--gradient-primary);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;margin-bottom:12px}.create-subtitle{font-size:18px;color:var(--text-secondary);font-weight:600}.form-section{background:var(--bg-secondary);border-radius:20px;padding:32px;margin-bottom:32px;box-shadow:0 8px 32px var(--shadow-color);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid var(--border-color)}.form-group{margin-bottom:24px}.form-label{display:block;font-size:14px;font-weight:700;color:var(--text-primary);margin-bottom:8px}.form-input,.form-textarea{width:100%;padding:12px 16px;border:1px solid var(--border-color);border-radius:12px;font-size:16px;transition:all .3s ease;background:var(--bg-secondary);color:var(--text-primary);box-shadow:0 2px 8px var(--shadow-color)}.form-input:focus,.form-textarea:focus{outline:none;border-color:var(--text-accent);box-shadow:0 4px 16px #667eea33;transform:translateY(-1px)}.form-textarea{resize:vertical;min-height:80px}.form-error{color:#dc2626;font-size:14px;margin-top:4px}.cards-section{background:rgba(255,255,255,.95);border-radius:20px;padding:32px;margin-bottom:32px;box-shadow:0 8px 32px #0000001a;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid rgba(255,255,255,.2)}.cards-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:24px}.cards-title{font-size:20px;font-weight:600;color:#1f2937}.card-count{font-size:14px;color:#6b7280;background:#f3f4f6;padding:4px 12px;border-radius:20px}.add-card-button{background:linear-gradient(135deg,#667eea 0%,#764ba2 100%);color:#fff;border:none;border-radius:12px;padding:10px 20px;font-size:14px;font-weight:700;cursor:pointer;transition:all .3s ease;display:inline-flex;align-items:center;gap:8px;box-shadow:0 4px 12px #667eea4d}.add-card-button:hover{transform:translateY(-2px);box-shadow:0 8px 20px #667eea66}.cards-grid{display:grid;gap:20px}.card-item{border:1px solid rgba(255,255,255,.2);border-radius:16px;padding:24px;background:rgba(255,255,255,.95);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);box-shadow:0 8px 32px #0000001a;transition:all .3s ease}.card-item:hover{transform:translateY(-2px);box-shadow:0 12px 40px #00000026;border-color:#667eea4d}.card-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:16px}.card-number{font-size:14px;font-weight:700;color:#667eea;background:linear-gradient(135deg,#667eea,#764ba2);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent}.remove-card-button{background:linear-gradient(135deg,rgba(239,68,68,.1),rgba(220,38,38,.1));border:1px solid rgba(239,68,68,.2);color:#ef4444;cursor:pointer;padding:10px;border-radius:12px;transition:all .3s ease;display:flex;align-items:center;justify-content:center;-webkit-backdrop-filter:blur(5px);backdrop-filter:blur(5px)}.remove-card-button:hover{background:linear-gradient(135deg,rgba(239,68,68,.2),rgba(220,38,38,.2));transform:translateY(-2px);color:#dc2626;box-shadow:0 8px 24px #ef44444d}.card-inputs{display:grid;grid-template-columns:1fr 1fr;gap:16px}.card-input-group{display:flex;flex-direction:column}.card-input-label{font-size:13px;font-weight:700;color:#667eea;margin-bottom:8px;background:linear-gradient(135deg,#667eea,#764ba2);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent}.card-input{padding:14px 16px;border:1px solid rgba(255,255,255,.3);border-radius:12px;font-size:14px;transition:all .3s ease;min-height:70px;resize:vertical;background:rgba(255,255,255,.8);-webkit-backdrop-filter:blur(5px);backdrop-filter:blur(5px);box-shadow:0 4px 16px #0000000d}.card-input:focus{outline:none;border-color:#667eea;box-shadow:0 8px 32px #667eea33;background:rgba(255,255,255,.95)}.card-input.empty{border-color:#f87171;background:rgba(254,242,242,.9)}.form-actions{display:flex;gap:16px;justify-content:center;padding:32px;background:rgba(255,255,255,.95);border-radius:20px;box-shadow:0 8px 32px #0000001a;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border:1px solid rgba(255,255,255,.2)}.action-button{padding:14px 32px;border-radius:12px;font-size:16px;font-weight:700;cursor:pointer;transition:all .3s ease;border:none;min-width:140px;display:inline-flex;align-items:center;justify-content:center;gap:8px;position:relative;overflow:hidden}.action-button:before{content:"";position:absolute;top:0;left:-100%;width:100%;height:100%;background:linear-gradient(90deg,transparent,rgba(255,255,255,.2),transparent);transition:left .5s ease}.action-button:hover:before{left:100%}.action-button.primary{background:linear-gradient(135deg,#667eea 0%,#764ba2 100%);color:#fff;box-shadow:0 8px 24px #667eea4d}.action-button.primary:hover{transform:translateY(-2px);box-shadow:0 12px 32px #667eea66}.action-button.primary:disabled{opacity:.6;cursor:not-allowed;transform:none;box-shadow:0 4px 12px #667eea33}.action-button.secondary{background:linear-gradient(135deg,#6b7280 0%,#4b5563 100%);color:#fff;box-shadow:0 8px 24px #6b72804d}.action-button.secondary:hover{transform:translateY(-2px);box-shadow:0 12px 32px #6b728066}.loading-spinner{width:16px;height:16px;border:2px solid rgba(255,255,255,.3);border-radius:50%;border-top-color:#fff;animation:spin 1s ease-in-out infinite}@keyframes spin{to{transform:rotate(360deg)}}.validation-summary{background:linear-gradient(135deg,rgba(254,242,242,.9),rgba(252,226,226,.9));border:1px solid rgba(254,202,202,.5);border-radius:16px;padding:20px;margin-bottom:24px;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);box-shadow:0 8px 32px #dc26261a}.validation-title{font-size:14px;font-weight:700;color:#dc2626;margin-bottom:12px}.validation-list{list-style:none;padding:0;margin:0}.validation-item{font-size:14px;color:#dc2626;margin-bottom:4px}.validation-item:before{content:"• ";margin-right:4px}@media (max-width: 640px){.create-deck{padding:16px}.form-section,.cards-section{padding:20px}.create-title{font-size:28px}.card-inputs{grid-template-columns:1fr;gap:12px}.cards-header{flex-direction:column;gap:12px;align-items:stretch}.add-card-button{width:100%}.form-actions{flex-direction:column;padding:20px}.action-button{width:100%}}:root{--bg-primary: #f9fafb;--bg-secondary: #ffffff;--bg-tertiary: #f3f4f6;--text-primary: #111827;--text-secondary: #6b7280;--text-accent: #667eea;--border-color: #e5e7eb;--shadow-color: rgba(0, 0, 0, .1);--gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);--gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%)}[data-theme=dark]{--bg-primary: #0f172a;--bg-secondary: #1e293b;--bg-tertiary: #334155;--text-primary: #f8fafc;--text-secondary: #94a3b8;--text-accent: #818cf8;--border-color: #475569;--shadow-color: rgba(0, 0, 0, .3);--gradient-primary: linear-gradient(135deg, #818cf8 0%, #c084fc 100%);--gradient-secondary: linear-gradient(135deg, #06b6d4 0%, #3b82f6 100%)}.app{min-height:100vh;background:var(--bg-primary);color:var(--text-primary);display:flex;flex-direction:column;transition:background .3s ease,color .3s ease}.main-content{flex:1;padding:20px}body{margin:0;padding:0;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;background:var(--bg-primary);color:var(--text-primary);transition:background .3s ease,color .3s ease}.theme-toggle{background:var(--bg-secondary);border:1px solid var(--border-color);border-radius:12px;padding:8px;cursor:pointer;transition:all .3s ease;color:var(--text-primary);display:flex;align-items:center;justify-content:center;box-shadow:0 2px 8px var(--shadow-color)}.theme-toggle:hover{transform:translateY(-1px);box-shadow:0 4px 16px var(--shadow-color)}.btn-primary{background:var(--gradient-primary);color:#fff;border:none;border-radius:8px;padding:12px 24px;font-size:16px;font-weight:600;cursor:pointer;transition:all .2s}.btn-primary:hover{transform:translateY(-1px);filter:brightness(1.1)}.btn-secondary{background:var(--bg-secondary);color:var(--text-primary);border:1px solid var(--border-color);border-radius:8px;padding:8px 16px;font-size:14px;cursor:pointer;transition:all .2s}.btn-secondary:hover{background:var(--bg-tertiary);border-color:var(--text-secondary)}@media (max-width: 640px){.main-content{padding:16px}}*{box-sizing:border-box}body{margin:0;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen,Ubuntu,Cantarell,Fira Sans,Droid Sans,Helvetica Neue,sans-serif;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;background:var(--bg-primary);color:var(--text-primary);transition:background .3s ease,color .3s ease}#root{min-height:100vh}@media (prefers-reduced-motion: reduce){*,*:before,*:after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important;scroll-behavior:auto!important}}:focus{outline:2px solid #3b82f6;outline-offset:2px}:focus:not(:focus-visible){outline:none}:focus-visible{outline:2px solid #3b82f6;outline-offset:2px}.btn{display:inline-flex;align-items:center;justify-content:center;padding:.5rem 1rem;border:none;border-radius:.375rem;font-size:.875rem;font-weight:500;cursor:pointer;transition:all .2s ease-in-out;text-decoration:none}.btn:disabled{opacity:.5;cursor:not-allowed}.btn-primary{background-color:#3b82f6;color:#fff}.btn-primary:hover:not(:disabled){background-color:#2563eb}.btn-secondary{background-color:#e2e8f0;color:#475569}.btn-secondary:hover:not(:disabled){background-color:#cbd5e1}.btn-danger{background-color:#ef4444;color:#fff}.btn-danger:hover:not(:disabled){background-color:#dc2626}.btn-success{background-color:#10b981;color:#fff}.btn-success:hover:not(:disabled){background-color:#059669}.btn-warning{background-color:#f59e0b;color:#fff}.btn-warning:hover:not(:disabled){background-color:#d97706}.card{background:var(--bg-secondary);color:var(--text-primary);border:1px solid var(--border-color);border-radius:.5rem;box-shadow:0 1px 3px 0 var(--shadow-color),0 1px 2px -1px var(--shadow-color);overflow:hidden}.card-header{padding:1rem 1.5rem;border-bottom:1px solid var(--border-color)}.card-body{padding:1.5rem}.card-footer{padding:1rem 1.5rem;border-top:1px solid var(--border-color);background-color:var(--bg-tertiary)}.form-group{margin-bottom:1rem}.form-label{display:block;margin-bottom:.25rem;font-size:.875rem;font-weight:500;color:var(--text-primary)}.form-input{display:block;width:100%;padding:.5rem .75rem;border:1px solid var(--border-color);background:var(--bg-secondary);color:var(--text-primary);border-radius:.375rem;font-size:.875rem;transition:border-color .2s}.form-input:focus{border-color:var(--text-accent);outline:none;box-shadow:0 0 0 3px #667eea1a}.form-textarea{resize:vertical;min-height:4rem}.form-select{background-image:url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 20 20'%3e%3cpath stroke='%236b7280' stroke-linecap='round' stroke-linejoin='round' stroke-width='1.5' d='m6 8 4 4 4-4'/%3e%3c/svg%3e");background-position:right .5rem center;background-repeat:no-repeat;background-size:1.5em 1.5em;padding-right:2.5rem;-webkit-appearance:none;-moz-appearance:none;appearance:none}.container{max-width:1200px;margin:0 auto;padding:0 1rem}.grid{display:grid;gap:1rem}.grid-cols-1{grid-template-columns:repeat(1,minmax(0,1fr))}.grid-cols-2{grid-template-columns:repeat(2,minmax(0,1fr))}.grid-cols-3{grid-template-columns:repeat(3,minmax(0,1fr))}.grid-cols-4{grid-template-columns:repeat(4,minmax(0,1fr))}@media (min-width: 640px){.sm\\:grid-cols-2{grid-template-columns:repeat(2,minmax(0,1fr))}.sm\\:grid-cols-3{grid-template-columns:repeat(3,minmax(0,1fr))}}@media (min-width: 768px){.md\\:grid-cols-3{grid-template-columns:repeat(3,minmax(0,1fr))}.md\\:grid-cols-4{grid-template-columns:repeat(4,minmax(0,1fr))}}@media (min-width: 1024px){.lg\\:grid-cols-4{grid-template-columns:repeat(4,minmax(0,1fr))}.lg\\:grid-cols-5{grid-template-columns:repeat(5,minmax(0,1fr))}}.flex{display:flex}.items-center{align-items:center}.justify-between{justify-content:space-between}.justify-center{justify-content:center}.gap-2{gap:.5rem}.gap-4{gap:1rem}.mb-4{margin-bottom:1rem}.mb-6{margin-bottom:1.5rem}.text-center{text-align:center}.text-lg{font-size:1.125rem}.text-xl{font-size:1.25rem}.text-2xl{font-size:1.5rem}.font-bold{font-weight:700}.font-semibold{font-weight:600}.text-gray-500{color:#6b7280}.text-gray-600{color:#4b5563}.text-gray-700{color:#374151}.text-green-600{color:#059669}.text-red-600{color:#dc2626}.text-blue-600{color:#2563eb}.bg-green-100{background-color:#dcfce7}.bg-red-100{background-color:#fee2e2}.bg-blue-100{background-color:#dbeafe}.bg-yellow-100{background-color:#fef3c7}.rounded{border-radius:.25rem}.rounded-lg{border-radius:.5rem}.p-2{padding:.5rem}.p-4{padding:1rem}.px-2{padding-left:.5rem;padding-right:.5rem}.px-3{padding-left:.75rem;padding-right:.75rem}.py-1{padding-top:.25rem;padding-bottom:.25rem}.py-2{padding-top:.5rem;padding-bottom:.5rem}.w-full{width:100%}.h-full{height:100%}.min-h-screen{min-height:100vh}.fade-in{animation:fadeIn .3s ease-in-out}@keyframes fadeIn{0%{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}.flip-card{perspective:1000px}.flip-card-inner{position:relative;width:100%;height:100%;text-align:center;transition:transform .6s;transform-style:preserve-3d}.flip-card.flipped .flip-card-inner{transform:rotateY(180deg)}.flip-card-front,.flip-card-back{position:absolute;width:100%;height:100%;backface-visibility:hidden;border-radius:.5rem;display:flex;align-items:center;justify-content:center;padding:2rem;background:white;border:1px solid #e2e8f0}.flip-card-back{transform:rotateY(180deg)}.progress-bar{width:100%;height:.5rem;background-color:#e2e8f0;border-radius:.25rem;overflow:hidden}.progress-bar-fill{height:100%;background-color:#3b82f6;transition:width .3s ease-in-out}.toast{position:fixed;top:1rem;right:1rem;background:var(--bg-secondary);color:var(--text-primary);border:1px solid var(--border-color);border-radius:.5rem;box-shadow:0 10px 15px -3px var(--shadow-color),0 4px 6px -4px var(--shadow-color);padding:1rem;border-left:4px solid var(--text-accent);max-width:400px;z-index:1000;animation:slideIn .3s ease-out}.toast.success{border-left-color:#10b981}.toast.error{border-left-color:#ef4444}.toast.warning{border-left-color:#f59e0b}@keyframes slideIn{0%{transform:translate(100%);opacity:0}to{transform:translate(0);opacity:1}}.study-container{min-height:100vh;display:flex;flex-direction:column}.study-header{background:var(--bg-secondary);border-bottom:1px solid var(--border-color);padding:1rem 0}.study-content{flex:1;display:flex;align-items:center;justify-content:center;padding:2rem}.study-card{width:100%;max-width:600px;min-height:400px;cursor:pointer}.study-actions{background:var(--bg-secondary);border-top:1px solid var(--border-color);padding:1rem 0}.answer-buttons{display:flex;gap:1rem;justify-content:center;flex-wrap:wrap}.answer-btn{min-width:120px;padding:.75rem 1rem;border-radius:.5rem;font-weight:600;position:relative}.answer-btn .interval{display:block;font-size:.75rem;opacity:.8;margin-top:.25rem}.space-y-1>*+*{margin-top:.25rem}.space-y-2>*+*{margin-top:.5rem}.space-y-3>*+*{margin-top:.75rem}.space-y-4>*+*{margin-top:1rem}.space-y-6>*+*{margin-top:1.5rem}.space-y-8>*+*{margin-top:2rem}.text-xs{font-size:.75rem}.text-sm{font-size:.875rem}.font-medium{font-weight:500}.italic{font-style:italic}.text-gray-300{color:#d1d5db}.text-gray-400{color:#9ca3af}.text-gray-800{color:#1f2937}.text-gray-900{color:#111827}.text-blue-700{color:#1d4ed8}.text-blue-800{color:#1e40af}.text-blue-900{color:#1e3a8a}.text-green-700{color:#15803d}.text-red-500{color:#ef4444}.text-red-700{color:#b91c1c}.text-red-800{color:#991b1b}.text-yellow-600{color:#ca8a04}.text-yellow-700{color:#a16207}.text-orange-600{color:#ea580c}.text-purple-600{color:#9333ea}.bg-gray-50{background-color:#f9fafb}.bg-blue-50{background-color:#eff6ff}.bg-blue-600{background-color:#2563eb}.bg-green-50{background-color:#f0fdf4}.bg-green-500{background-color:#22c55e}.bg-red-50{background-color:#fef2f2}.bg-yellow-50{background-color:#fefce8}.bg-purple-50{background-color:#faf5ff}.bg-orange-500{background-color:#f97316}.border{border:1px solid #e5e7eb}.border-b{border-bottom:1px solid #e5e7eb}.border-2{border-width:2px}.border-dashed{border-style:dashed}.border-gray-200{border-color:#e5e7eb}.border-gray-300{border-color:#d1d5db}.border-blue-200{border-color:#bfdbfe}.border-blue-500{border-color:#3b82f6}.border-blue-600{border-color:#2563eb}.border-red-200{border-color:#fecaca}.border-yellow-200{border-color:#fde68a}.border-transparent{border-color:transparent}.border-b-2{border-bottom-width:2px}.rounded-full{border-radius:9999px}.shadow-lg{box-shadow:0 10px 15px -3px #0000001a,0 4px 6px -2px #0000000d}.transition-all{transition:all .15s ease-in-out}.transition-colors{transition:color .15s ease-in-out,background-color .15s ease-in-out,border-color .15s ease-in-out}.duration-300{transition-duration:.3s}.hover\:bg-gray-50:hover{background-color:#f9fafb}.hover\:bg-blue-700:hover{background-color:#1d4ed8}.hover\:text-gray-700:hover{color:#374151}.hover\:border-gray-400:hover{border-color:#9ca3af}.hover\:shadow-md:hover{box-shadow:0 4px 6px -1px #0000001a,0 2px 4px -1px #0000000f}.focus\:outline-none:focus{outline:none}.focus\:ring-2:focus{box-shadow:0 0 0 2px #3b82f680}.focus\:border-blue-500:focus{border-color:#3b82f6}.m-0{margin:0}.mb-1{margin-bottom:.25rem}.mb-2{margin-bottom:.5rem}.mb-3{margin-bottom:.75rem}.mt-1{margin-top:.25rem}.mt-2{margin-top:.5rem}.mt-3{margin-top:.75rem}.mt-4{margin-top:1rem}.mt-6{margin-top:1.5rem}.mt-8{margin-top:2rem}.mx-auto{margin-left:auto;margin-right:auto}.p-3{padding:.75rem}.p-6{padding:1.5rem}.p-8{padding:2rem}.px-4{padding-left:1rem;padding-right:1rem}.px-6{padding-left:1.5rem;padding-right:1.5rem}.py-3{padding-top:.75rem;padding-bottom:.75rem}.py-4{padding-top:1rem;padding-bottom:1rem}.py-8{padding-top:2rem;padding-bottom:2rem}.w-5{width:1.25rem}.w-12{width:3rem}.h-2{height:.5rem}.h-5{height:1.25rem}.h-8{width:2rem;height:2rem}.h-12{width:3rem;height:3rem}.h-64{height:16rem}.min-h-60{min-height:60px}.min-h-100{min-height:100px}.max-w-sm{max-width:24rem}.max-w-4xl{max-width:56rem}.hidden{display:none}.block{display:block}.relative{position:relative}.fixed{position:fixed}.absolute{position:absolute}.inset-0{top:0;right:0;bottom:0;left:0}.z-50{z-index:50}.text-left{text-align:left}.text-right{text-align:right}.whitespace-pre-wrap{white-space:pre-wrap}.items-start{align-items:flex-start}.justify-end{justify-content:flex-end}.flex-col{flex-direction:column}.gap-1{gap:.25rem}.gap-3{gap:.75rem}.gap-6{gap:1.5rem}.gap-8{gap:2rem}.form-checkbox{width:1rem;height:1rem;color:#2563eb;border:1px solid #d1d5db;border-radius:.25rem;background-color:#fff}.form-checkbox:focus{outline:none;box-shadow:0 0 0 3px #3b82f61a}table{width:100%;border-collapse:collapse}th,td{padding:.75rem;text-align:left;border-bottom:1px solid var(--border-color);color:var(--text-primary)}th{font-weight:600;background-color:var(--bg-tertiary)}.overflow-x-auto{overflow-x:auto}.kbd{display:inline-block;padding:.125rem .375rem;font-size:.75rem;font-family:ui-monospace,SFMono-Regular,monospace;background-color:var(--bg-tertiary);border:1px solid var(--border-color);border-radius:.25rem;color:var(--text-primary)}.spinner{display:inline-block;width:3rem;height:3rem;border:3px solid var(--border-color);border-top:3px solid var(--text-accent);border-radius:50%;animation:spin 1s linear infinite}@keyframes spin{0%{transform:rotate(0)}to{transform:rotate(360deg)}}.btn-lg{padding:.75rem 1.5rem;font-size:1rem}.btn-sm{padding:.375rem .75rem;font-size:.75rem}@media (min-width: 640px){.sm\:grid-cols-2{grid-template-columns:repeat(2,minmax(0,1fr))}.sm\:grid-cols-3{grid-template-columns:repeat(3,minmax(0,1fr))}.sm\:flex-row{flex-direction:row}.sm\:items-center{align-items:center}}@media (min-width: 768px){.md\:grid-cols-2{grid-template-columns:repeat(2,minmax(0,1fr))}.md\:text-2xl{font-size:1.5rem}.md\:flex-row{flex-direction:row}}@media (min-width: 1024px){.lg\:grid-cols-2{grid-template-columns:repeat(2,minmax(0,1fr))}.lg\:grid-cols-3{grid-template-columns:repeat(3,minmax(0,1fr))}}.slide-up{animation:slideUp .3s ease-out}@keyframes slideUp{0%{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}::-webkit-scrollbar{width:8px;height:8px}::-webkit-scrollbar-track{background:#f1f1f1;border-radius:4px}::-webkit-scrollbar-thumb{background:#c1c1c1;border-radius:4px}::-webkit-scrollbar-thumb:hover{background:#a8a8a8}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}@media (max-width: 640px){.answer-buttons{flex-direction:column;align-items:center}.answer-btn{width:100%;max-width:300px}.study-card{min-height:300px}.grid-cols-1{grid-template-columns:1fr}.container{padding:0 .5rem}.card-body{padding:1rem}h1{font-size:1.75rem}h2{font-size:1.5rem}}