:root{--primary:#2563eb;--primary-hover:#1d4ed8;--primary-light:#dbeafe;--secondary:#6b7280;--success:#10b981;--success-light:#d1fae5;--warning:#f59e0b;--warning-light:#fef3c7;--danger:#ef4444;--danger-light:#fee2e2;--bg:#f9fafb;--bg-card:#fff;--text:#1f2937;--text-secondary:#6b7280;--border:#e5e7eb;--border-focus:#93c5fd;--shadow:0 1px 3px #0000001a;--shadow-lg:0 4px 12px #0000001a;--radius:8px;--radius-lg:12px;--sidebar-width:200px;color:var(--text);font-family:Hiragino Kaku Gothic ProN,Noto Sans JP,system-ui,sans-serif;font-size:16px;line-height:1.5}@media (prefers-color-scheme:dark){:root{--primary:#3b82f6;--primary-hover:#60a5fa;--primary-light:#1e3a5f;--bg:#111827;--bg-card:#1f2937;--text:#f3f4f6;--text-secondary:#9ca3af;--border:#374151;--border-focus:#60a5fa;--shadow:0 1px 3px #0000004d;--shadow-lg:0 4px 12px #0000004d;--success-light:#064e3b;--warning-light:#78350f;--danger-light:#7f1d1d}}*{box-sizing:border-box;margin:0;padding:0}body{background:var(--bg);min-height:100vh}#root{min-height:100vh}.app-layout{min-height:100vh;display:flex}.sidebar{width:var(--sidebar-width);background:var(--bg-card);border-right:1px solid var(--border);z-index:100;padding:20px 0;position:fixed;top:0;bottom:0;left:0;overflow-y:auto}.sidebar-header{border-bottom:1px solid var(--border);margin-bottom:8px;padding:0 20px 20px}.sidebar-header h1{color:var(--primary);margin:0;font-size:22px;font-weight:700;line-height:1.3}.sidebar-header p{color:var(--text-secondary);font-size:13px}.nav-list{list-style:none}.nav-link{color:var(--text-secondary);align-items:center;gap:10px;padding:10px 20px;font-size:14px;text-decoration:none;transition:all .15s;display:flex}.nav-link:hover{background:var(--primary-light);color:var(--primary)}.nav-link.active{background:var(--primary-light);color:var(--primary);border-right:3px solid var(--primary);font-weight:600}.nav-icon{text-align:center;width:24px;font-size:18px}.main-content{margin-left:var(--sidebar-width);flex:1;max-width:900px;padding:24px}.bottom-nav{display:none}@media (width<=768px){.sidebar{display:none}.main-content{margin-left:0;padding:16px 16px 80px}.bottom-nav{background:var(--bg-card);border-top:1px solid var(--border);z-index:100;-webkit-overflow-scrolling:touch;display:flex;position:fixed;bottom:0;left:0;right:0;overflow-x:auto}.bottom-nav-link{color:var(--text-secondary);flex-direction:column;flex:1;align-items:center;gap:2px;min-width:48px;padding:8px 4px;font-size:10px;text-decoration:none;display:flex}.bottom-nav-link .nav-icon{font-size:20px}.bottom-nav-link.active{color:var(--primary);font-weight:600}}.btn{border-radius:var(--radius);cursor:pointer;border:none;justify-content:center;align-items:center;gap:6px;padding:10px 20px;font-family:inherit;font-size:14px;font-weight:500;transition:all .15s;display:inline-flex}.btn-primary{background:var(--primary);color:#fff}.btn-primary:hover{background:var(--primary-hover)}.btn-secondary{background:var(--border);color:var(--text)}.btn-secondary:hover{background:var(--text-secondary);color:#fff}.btn-success{background:var(--success);color:#fff}.btn-warning{background:var(--warning);color:#fff}.btn-danger{background:var(--danger);color:#fff}.btn-small{padding:6px 12px;font-size:12px}.btn-large{padding:14px 32px;font-size:16px}.btn-icon{padding:6px 10px;font-size:16px;line-height:1}h2{color:var(--text);margin-bottom:20px;font-size:22px;font-weight:700}h3{color:var(--text);margin-bottom:12px;font-size:16px;font-weight:600}.stats-grid{grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:12px;margin-bottom:24px;display:grid}.stat-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);text-align:center;box-shadow:var(--shadow);padding:20px}.stat-number{color:var(--primary);font-size:32px;font-weight:700}.stat-due .stat-number{color:var(--warning)}.stat-mastered .stat-number{color:var(--success)}.stat-learning .stat-number{color:#8b5cf6}.stat-label{color:var(--text-secondary);margin-top:4px;font-size:13px}.progress-section{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow);margin-bottom:24px;padding:20px}.progress-bar-container{background:var(--border);border-radius:6px;width:100%;height:12px;margin:12px 0 8px;overflow:hidden}.progress-bar{background:var(--primary);border-radius:6px;min-width:0;height:100%;transition:width .3s}.progress-text{color:var(--text-secondary);font-size:13px}.mastery-breakdown{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow);margin-bottom:24px;padding:20px}.mastery-bar-item{align-items:center;gap:12px;margin-bottom:8px;display:flex}.mastery-bar-label{text-align:right;width:60px;color:var(--text-secondary);font-size:13px}.mastery-bar-track{background:var(--border);border-radius:4px;flex:1;height:8px;overflow:hidden}.mastery-bar-fill{border-radius:4px;height:100%;transition:width .3s}.mastery-bar-count{width:30px;color:var(--text-secondary);font-size:13px}.quick-actions{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow);padding:20px}.action-buttons{flex-wrap:wrap;gap:12px;display:flex}.empty-state{text-align:center;color:var(--text-secondary);padding:40px 20px}.empty-state p{margin-bottom:16px}.vocab-header{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:12px;margin-bottom:16px;display:flex}.vocab-filters{flex-wrap:wrap;gap:8px;margin-bottom:16px;display:flex}.search-input,.vocab-filters select{border:1px solid var(--border);border-radius:var(--radius);background:var(--bg-card);color:var(--text);padding:8px 12px;font-family:inherit;font-size:14px}.search-input{flex:1;min-width:200px}.search-input:focus,.vocab-filters select:focus{border-color:var(--border-focus);outline:none;box-shadow:0 0 0 3px #3b82f61a}.vocab-cards{gap:12px;display:grid}.vocab-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow);padding:16px}.vocab-card-main{flex-wrap:wrap;align-items:baseline;gap:12px;margin-bottom:8px;display:flex}.vocab-chinese{color:var(--text);font-size:24px;font-weight:700}.vocab-pinyin{color:var(--text-secondary);font-size:14px}.vocab-japanese{color:var(--primary);font-size:16px;font-weight:500}.vocab-card-meta{flex-wrap:wrap;gap:6px;margin-bottom:8px;display:flex}.tag{background:var(--primary-light);color:var(--primary);border-radius:12px;padding:2px 8px;font-size:11px;display:inline-block}.tag-pos{background:var(--warning-light);color:var(--warning)}.mastery-badge{color:#fff;border-radius:12px;padding:2px 8px;font-size:11px;display:inline-block}.vocab-example{color:var(--text-secondary);margin-bottom:8px;font-size:13px}.example-label{font-weight:600}.vocab-card-actions{justify-content:flex-end;gap:6px;display:flex}.vocab-count{text-align:center;color:var(--text-secondary);margin-top:16px;font-size:13px}.modal-overlay{z-index:200;background:#00000080;justify-content:center;align-items:center;padding:16px;display:flex;position:fixed;inset:0}.modal{background:var(--bg-card);border-radius:var(--radius-lg);width:100%;max-width:600px;max-height:90vh;box-shadow:var(--shadow-lg);padding:24px;overflow-y:auto}.modal h3{margin-bottom:20px;font-size:18px}.form-row{grid-template-columns:1fr 1fr;gap:12px;display:grid}@media (width<=500px){.form-row{grid-template-columns:1fr}}.form-group{margin-bottom:16px}.form-group label{color:var(--text-secondary);margin-bottom:4px;font-size:13px;font-weight:600;display:block}.form-group input,.form-group select{border:1px solid var(--border);border-radius:var(--radius);background:var(--bg);width:100%;color:var(--text);padding:8px 12px;font-family:inherit;font-size:14px}.form-group input:focus,.form-group select:focus{border-color:var(--border-focus);outline:none;box-shadow:0 0 0 3px #3b82f61a}.example-sentence-group{grid-template-columns:1fr 1fr 1fr auto;gap:6px;margin-bottom:8px;display:grid}@media (width<=500px){.example-sentence-group{grid-template-columns:1fr}}.example-sentence-group input{border:1px solid var(--border);border-radius:var(--radius);background:var(--bg);color:var(--text);padding:6px 10px;font-family:inherit;font-size:13px}.form-actions{justify-content:flex-end;gap:8px;margin-top:20px;display:flex}.flashcard-page{max-width:500px;margin:0 auto}.flashcard-header{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:8px;margin-bottom:16px;display:flex}.mode-toggle{gap:4px;display:flex}.flashcard-progress{color:var(--text-secondary);align-items:center;gap:8px;margin-bottom:16px;font-size:14px;display:flex}.flashcard{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);cursor:pointer;perspective:1000px;min-height:280px;box-shadow:var(--shadow-lg);margin-bottom:20px}.flashcard-inner{width:100%;min-height:280px;transform-style:preserve-3d;transition:transform .5s;position:relative}.flashcard.flipped .flashcard-inner{transform:rotateY(180deg)}.flashcard-front,.flashcard-back{backface-visibility:hidden;border-radius:var(--radius-lg);flex-direction:column;justify-content:center;align-items:center;padding:32px;display:flex;position:absolute;inset:0}.flashcard-back{transform:rotateY(180deg)}.flashcard-main{margin-bottom:8px;font-size:36px;font-weight:700}.flashcard-sub{color:var(--text-secondary);font-size:16px}.flashcard-hint{color:var(--text-secondary);font-size:12px;position:absolute;bottom:16px}.flashcard-example{text-align:center;margin-top:16px;font-size:14px}.example-pinyin{color:var(--text-secondary);font-size:13px}.example-jp{color:var(--primary);font-size:13px}.flashcard-actions{justify-content:center;gap:12px;display:flex}.flashcard-actions .btn{flex:1;max-width:140px}.session-complete{text-align:center;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow);padding:32px}.session-results{justify-content:center;gap:32px;margin:24px 0;display:flex}.result-item{flex-direction:column;align-items:center;display:flex}.result-number{font-size:36px;font-weight:700}.result-correct .result-number{color:var(--success)}.result-incorrect .result-number{color:var(--danger)}.quiz-page{max-width:600px;margin:0 auto}.quiz-start{text-align:center;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow);padding:32px}.quiz-start p{color:var(--text-secondary);margin-bottom:20px}.quiz-start .mode-toggle{justify-content:center;margin-bottom:24px}.quiz-header{justify-content:space-between;align-items:center;margin-bottom:16px;display:flex}.quiz-progress{color:var(--text-secondary);font-size:14px}.quiz-question{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);text-align:center;box-shadow:var(--shadow);margin-bottom:16px;padding:32px}.quiz-question-main{font-size:32px;font-weight:700}.quiz-question-sub{color:var(--text-secondary);margin-top:4px;font-size:14px}.quiz-options{gap:8px;margin-bottom:16px;display:grid}.quiz-option{background:var(--bg-card);border:2px solid var(--border);border-radius:var(--radius);cursor:pointer;text-align:left;width:100%;color:var(--text);padding:16px;font-family:inherit;font-size:16px;transition:all .15s}.quiz-option:hover{border-color:var(--primary);background:var(--primary-light)}.quiz-option.correct{border-color:var(--success);background:var(--success-light)}.quiz-option.incorrect{border-color:var(--danger);background:var(--danger-light)}.quiz-feedback{text-align:center;padding:16px}.feedback-correct{color:var(--success);margin-bottom:12px;font-size:18px;font-weight:600}.feedback-incorrect{color:var(--danger);margin-bottom:8px;font-size:18px;font-weight:600}.quiz-results-list{text-align:left;margin:16px 0}.quiz-result-item{border-bottom:1px solid var(--border);align-items:center;gap:8px;padding:8px 0;font-size:14px;display:flex}.quiz-result-icon{width:20px;font-weight:700}.quiz-result-item.correct .quiz-result-icon{color:var(--success)}.quiz-result-item.incorrect .quiz-result-icon{color:var(--danger)}.quiz-result-word{min-width:60px;font-weight:600}.quiz-result-answer{color:var(--text-secondary)}.pinyin-page{max-width:500px;margin:0 auto}.pinyin-progress{color:var(--text-secondary);margin-bottom:16px;font-size:14px}.pinyin-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);text-align:center;box-shadow:var(--shadow);padding:32px}.pinyin-question{margin-bottom:8px;font-size:40px;font-weight:700}.pinyin-meaning{color:var(--text-secondary);margin-bottom:24px;font-size:16px}.pinyin-input{border:2px solid var(--border);border-radius:var(--radius);text-align:center;background:var(--bg);width:100%;color:var(--text);margin-bottom:12px;padding:12px 16px;font-family:inherit;font-size:18px}.pinyin-input:focus{border-color:var(--border-focus);outline:none}.pinyin-result{margin-top:16px}.pinyin-result p{margin-bottom:8px}.grammar-page{max-width:600px;margin:0 auto}.grammar-progress{color:var(--text-secondary);margin-bottom:16px;font-size:14px}.grammar-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow);padding:24px}.grammar-instruction{color:var(--text-secondary);margin-bottom:16px;font-size:14px}.grammar-sentence{margin-bottom:12px;font-size:20px;line-height:1.6}.grammar-blank{border-bottom:2px solid var(--primary);min-width:60px;color:var(--primary);margin:0 4px;font-weight:700;display:inline-block}.grammar-context{color:var(--text-secondary);margin-top:8px;font-size:14px}.grammar-translation{color:var(--text-secondary);margin-bottom:16px;font-size:14px}.grammar-hint{color:var(--warning);background:var(--warning-light);border-radius:var(--radius);margin-bottom:12px;padding:8px;font-size:14px}.grammar-input{border:2px solid var(--border);border-radius:var(--radius);background:var(--bg);width:100%;color:var(--text);margin-bottom:12px;padding:10px 14px;font-family:inherit;font-size:16px}.grammar-input:focus{border-color:var(--border-focus);outline:none}.grammar-buttons{justify-content:center;gap:8px;display:flex}.grammar-result{text-align:center;margin-top:16px}.grammar-full-sentence{background:var(--bg);border-radius:var(--radius);text-align:left;margin:12px 0;padding:12px;font-size:14px}.settings-page{max-width:600px}.settings-section{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius-lg);box-shadow:var(--shadow);margin-bottom:16px;padding:20px}.settings-section p{color:var(--text-secondary);margin-bottom:12px;font-size:14px}.settings-danger{border-color:var(--danger)}.import-options{margin-bottom:12px}.radio-label{cursor:pointer;padding:6px 0;font-size:14px;display:block}.radio-label input{margin-right:8px}.file-input{font-family:inherit;font-size:14px}.danger-action{border-bottom:1px solid var(--border);flex-wrap:wrap;justify-content:space-between;align-items:center;gap:16px;padding:12px 0;display:flex}.danger-action:last-child{border-bottom:none}.danger-action p{margin-bottom:0}.confirm-buttons{gap:8px;display:flex}.message{border-radius:var(--radius);justify-content:space-between;align-items:center;margin-bottom:16px;padding:12px 16px;font-size:14px;display:flex}.message.success{background:var(--success-light);color:var(--success)}.message.error{background:var(--danger-light);color:var(--danger)}.message-close{cursor:pointer;color:inherit;background:0 0;border:none;padding:0 4px;font-size:18px}