.nav{background:var(--color-bg-secondary);border-bottom:1px solid rgba(255,255,255,.05);position:sticky;top:0;z-index:100;-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px)}.nav-container{max-width:1200px;margin:0 auto;padding:var(--space-md) var(--space-lg);display:flex;align-items:center;justify-content:space-between}.nav-logo{display:flex;align-items:center;gap:var(--space-sm);text-decoration:none;color:var(--color-text-primary);font-weight:700;font-size:1.25rem}.logo-icon{font-size:1.5rem}.logo-text{background:var(--gradient-primary);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.nav-links{display:flex;gap:var(--space-md)}.nav-link{padding:var(--space-sm) var(--space-md);border-radius:var(--radius-md);text-decoration:none;color:var(--color-text-secondary);font-weight:500;transition:all var(--transition-fast)}.nav-link:hover{color:var(--color-text-primary);background:var(--color-bg-hover)}.nav-link.active{color:var(--color-accent-light);background:#6366f126}.home{padding-top:var(--space-xl);padding-bottom:var(--space-2xl)}.home-header{text-align:center;margin-bottom:var(--space-2xl)}.home-title{font-size:2.5rem;font-weight:800;margin-bottom:var(--space-md);display:flex;align-items:center;justify-content:center;gap:var(--space-sm)}.title-icon{font-size:2.5rem}.home-subtitle{font-size:1.125rem;color:var(--color-text-secondary)}.home-subtitle strong{color:var(--color-accent-light)}.section-title{font-size:1.25rem;margin-bottom:var(--space-lg);color:var(--color-text-secondary)}.mode-section{margin-bottom:var(--space-2xl)}.mode-grid{display:flex;flex-direction:column;gap:var(--space-md)}.mode-card{display:flex;align-items:center;gap:var(--space-lg);padding:var(--space-lg);background:var(--color-bg-card);border-radius:var(--radius-lg);border:1px solid rgba(255,255,255,.05);text-decoration:none;color:inherit;transition:all var(--transition-normal);position:relative}.mode-card:hover{transform:translate(8px);border-color:var(--color-accent);box-shadow:var(--shadow-glow)}.mode-icon{font-size:2.5rem;width:60px;height:60px;display:flex;align-items:center;justify-content:center;background:var(--color-bg-secondary);border-radius:var(--radius-md)}.mode-info{flex:1}.mode-title{font-size:1.25rem;font-weight:600;margin-bottom:var(--space-xs)}.mode-desc{color:var(--color-text-secondary);font-size:.875rem}.mode-arrow{font-size:1.5rem;color:var(--color-text-muted);transition:transform var(--transition-fast)}.mode-card:hover .mode-arrow{transform:translate(4px);color:var(--color-accent)}.mode-wrong:hover{border-color:var(--color-warning);box-shadow:0 0 20px #f59e0b4d}.wrong-badge{position:absolute;top:var(--space-md);right:var(--space-2xl);background:var(--color-error);color:#fff;font-size:.75rem;font-weight:600;padding:var(--space-xs) var(--space-sm);border-radius:var(--radius-full);min-width:24px;text-align:center}.stats-section{margin-bottom:var(--space-2xl)}.stats-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:var(--space-md)}@media(max-width:640px){.home-title{font-size:1.75rem}.stats-grid{grid-template-columns:repeat(2,1fr)}.mode-icon{width:48px;height:48px;font-size:1.75rem}}.question-card{max-width:700px;margin:0 auto}.question-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:var(--space-lg)}.question-id{font-size:.875rem;color:var(--color-text-muted)}.question-content{font-size:1.125rem;line-height:1.8;margin-bottom:var(--space-xl);padding:var(--space-md);background:var(--color-bg-secondary);border-radius:var(--radius-md);border-left:4px solid var(--color-accent)}.question-options{margin-bottom:var(--space-lg)}.btn-submit{width:100%;margin-top:var(--space-md)}.result-feedback{padding:var(--space-md);border-radius:var(--radius-md);margin-top:var(--space-lg);font-weight:600;animation:fadeIn var(--transition-normal) ease-out}.result-feedback.correct{background:#10b98126;color:var(--color-success);border:1px solid var(--color-success)}.result-feedback.wrong{background:#ef444426;color:var(--color-error);border:1px solid var(--color-error)}.correct-answer{margin-top:var(--space-sm);font-weight:400;color:var(--color-text-secondary)}.progress-container{margin-bottom:var(--space-lg)}.progress-info{display:flex;justify-content:space-between;margin-bottom:var(--space-sm);font-size:.875rem}.progress-text{color:var(--color-text-secondary)}.progress-correct{color:var(--color-success);font-weight:500}.quiz{padding-top:var(--space-lg);padding-bottom:var(--space-2xl)}.quiz-header{display:flex;align-items:center;gap:var(--space-md);margin-bottom:var(--space-lg)}.quiz-mode-label{font-size:.875rem;color:var(--color-text-muted)}.btn-sm{padding:var(--space-sm) var(--space-md);font-size:.875rem}.quiz-navigation{display:flex;justify-content:space-between;gap:var(--space-md);margin-top:var(--space-lg);max-width:700px;margin-left:auto;margin-right:auto}.quiz-navigation .btn{flex:1}.quiz-loading{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:60vh;gap:var(--space-md);color:var(--color-text-secondary)}.loading-spinner{width:48px;height:48px;border:3px solid var(--color-bg-hover);border-top-color:var(--color-accent);border-radius:50%;animation:spin 1s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}.quiz-empty{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:60vh;text-align:center}.empty-icon{font-size:4rem;margin-bottom:var(--space-lg)}.quiz-empty h2{margin-bottom:var(--space-sm)}.quiz-empty p{color:var(--color-text-secondary);margin-bottom:var(--space-xl)}.quiz-result{display:flex;align-items:center;justify-content:center;min-height:70vh}.result-card{text-align:center;padding:var(--space-2xl);max-width:500px;width:100%}.result-icon{font-size:4rem;margin-bottom:var(--space-lg)}.result-title{font-size:1.75rem;margin-bottom:var(--space-xl)}.result-stats{display:grid;grid-template-columns:repeat(4,1fr);gap:var(--space-md);margin-bottom:var(--space-xl)}.result-stat{padding:var(--space-md);background:var(--color-bg-secondary);border-radius:var(--radius-md)}.result-stat-value{font-size:1.75rem;font-weight:700;color:var(--color-accent-light)}.result-stat-value.correct{color:var(--color-success)}.result-stat-value.wrong{color:var(--color-error)}.result-stat-label{font-size:.75rem;color:var(--color-text-muted);margin-top:var(--space-xs)}.result-actions{display:flex;gap:var(--space-md)}.result-actions .btn{flex:1}@media(max-width:640px){.result-stats{grid-template-columns:repeat(2,1fr)}.result-actions{flex-direction:column}}.wrong-book{padding-top:var(--space-xl);padding-bottom:var(--space-2xl)}.wrong-header{margin-bottom:var(--space-xl)}.wrong-header h1{font-size:2rem;margin-bottom:var(--space-sm)}.wrong-subtitle{color:var(--color-text-secondary)}.wrong-action,.wrong-section{margin-bottom:var(--space-xl)}.section-title.mastered{color:var(--color-success)}.wrong-list{display:flex;flex-direction:column;gap:var(--space-md)}.wrong-item{padding:var(--space-md);transition:transform var(--transition-fast)}.wrong-item:hover{transform:translate(4px)}.wrong-item.mastered{opacity:.6}.wrong-item-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:var(--space-sm)}.wrong-count{font-size:.75rem;color:var(--color-error);font-weight:500}.mastered-badge{font-size:.75rem;color:var(--color-success);font-weight:500}.wrong-content{font-size:.875rem;color:var(--color-text-secondary);line-height:1.6}.wrong-empty{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:50vh;text-align:center}.wrong-empty .empty-icon{font-size:4rem;margin-bottom:var(--space-lg)}.wrong-empty h2{margin-bottom:var(--space-sm)}.wrong-empty p{color:var(--color-text-secondary);margin-bottom:var(--space-xl)}.mastered-list .wrong-item{background:var(--color-bg-secondary)}:root{--color-bg-primary: #0f0f1a;--color-bg-secondary: #1a1a2e;--color-bg-card: #252540;--color-bg-hover: #2f2f4f;--color-text-primary: #ffffff;--color-text-secondary: #a0a0b0;--color-text-muted: #6b6b80;--color-accent: #6366f1;--color-accent-light: #818cf8;--color-accent-dark: #4f46e5;--color-success: #10b981;--color-error: #ef4444;--color-warning: #f59e0b;--gradient-primary: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);--gradient-success: linear-gradient(135deg, #10b981 0%, #34d399 100%);--gradient-error: linear-gradient(135deg, #ef4444 0%, #f87171 100%);--shadow-sm: 0 2px 4px rgba(0, 0, 0, .3);--shadow-md: 0 4px 12px rgba(0, 0, 0, .4);--shadow-lg: 0 8px 24px rgba(0, 0, 0, .5);--shadow-glow: 0 0 20px rgba(99, 102, 241, .3);--radius-sm: 6px;--radius-md: 12px;--radius-lg: 20px;--radius-full: 9999px;--space-xs: 4px;--space-sm: 8px;--space-md: 16px;--space-lg: 24px;--space-xl: 32px;--space-2xl: 48px;--font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;--font-mono: "Fira Code", monospace;--transition-fast: .15s ease;--transition-normal: .25s ease;--transition-slow: .4s ease}*{margin:0;padding:0;box-sizing:border-box}html{font-size:16px}body{font-family:var(--font-sans);background:var(--color-bg-primary);color:var(--color-text-primary);line-height:1.6;min-height:100vh;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}#root{min-height:100vh;display:flex;flex-direction:column}.btn{display:inline-flex;align-items:center;justify-content:center;gap:var(--space-sm);padding:var(--space-md) var(--space-lg);border:none;border-radius:var(--radius-md);font-size:1rem;font-weight:600;cursor:pointer;transition:all var(--transition-normal);text-decoration:none}.btn-primary{background:var(--gradient-primary);color:#fff;box-shadow:var(--shadow-md),var(--shadow-glow)}.btn-primary:hover{transform:translateY(-2px);box-shadow:var(--shadow-lg),0 0 30px #6366f166}.btn-secondary{background:var(--color-bg-card);color:var(--color-text-primary);border:1px solid rgba(255,255,255,.1)}.btn-secondary:hover{background:var(--color-bg-hover);border-color:var(--color-accent)}.btn-success{background:var(--gradient-success);color:#fff}.btn-error{background:var(--gradient-error);color:#fff}.btn:disabled{opacity:.5;cursor:not-allowed;transform:none}.btn-lg{padding:var(--space-lg) var(--space-xl);font-size:1.125rem}.card{background:var(--color-bg-card);border-radius:var(--radius-lg);padding:var(--space-lg);box-shadow:var(--shadow-md);border:1px solid rgba(255,255,255,.05)}.card-glow{box-shadow:var(--shadow-md),var(--shadow-glow)}.container{max-width:800px;margin:0 auto;padding:var(--space-lg)}.progress-bar{width:100%;height:8px;background:var(--color-bg-secondary);border-radius:var(--radius-full);overflow:hidden}.progress-fill{height:100%;background:var(--gradient-primary);border-radius:var(--radius-full);transition:width var(--transition-normal)}.option{display:block;width:100%;padding:var(--space-md) var(--space-lg);margin-bottom:var(--space-sm);background:var(--color-bg-secondary);border:2px solid transparent;border-radius:var(--radius-md);cursor:pointer;transition:all var(--transition-fast);text-align:left;color:var(--color-text-primary);font-size:1rem}.option:hover:not(.option-disabled){background:var(--color-bg-hover);border-color:var(--color-accent);transform:translate(4px)}.option-selected{border-color:var(--color-accent);background:#6366f126}.option-correct{border-color:var(--color-success)!important;background:#10b98126!important}.option-wrong{border-color:var(--color-error)!important;background:#ef444426!important}.option-disabled{cursor:default;opacity:.7}@keyframes fadeIn{0%{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}@keyframes slideIn{0%{opacity:0;transform:translate(-20px)}to{opacity:1;transform:translate(0)}}@keyframes pulse{0%,to{opacity:1}50%{opacity:.7}}.animate-fadeIn{animation:fadeIn var(--transition-normal) ease-out}.animate-slideIn{animation:slideIn var(--transition-normal) ease-out}.tag{display:inline-block;padding:var(--space-xs) var(--space-sm);background:var(--color-bg-hover);border-radius:var(--radius-sm);font-size:.75rem;font-weight:500;color:var(--color-text-secondary)}.tag-accent{background:#6366f133;color:var(--color-accent-light)}.stat-card{text-align:center;padding:var(--space-lg)}.stat-value{font-size:2.5rem;font-weight:700;background:var(--gradient-primary);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}.stat-label{font-size:.875rem;color:var(--color-text-secondary);margin-top:var(--space-xs)}@media(max-width:640px){.container,.card{padding:var(--space-md)}.btn-lg{width:100%}}