/* ============================================================
   词库管理后台 - 全新UI设计
   大气 · 周正 · 色彩丰富
   ============================================================ */

/* ==================== CSS变量 ==================== */
:root {
    /* 主色调 - 深邃蓝紫 */
    --primary-color: #6366F1;
    --primary-dark: #4F46E5;
    --primary-light: #818CF8;
    --primary-gradient: linear-gradient(135deg, #6366F1 0%, #8B5CF6 100%);
    
    /* 辅助色 */
    --secondary-color: #64748B;
    --success-color: #10B981;
    --success-gradient: linear-gradient(135deg, #10B981 0%, #059669 100%);
    --danger-color: #EF4444;
    --danger-gradient: linear-gradient(135deg, #EF4444 0%, #DC2626 100%);
    --warning-color: #F59E0B;
    --warning-gradient: linear-gradient(135deg, #F59E0B 0%, #D97706 100%);
    --info-color: #06B6D4;
    --info-gradient: linear-gradient(135deg, #06B6D4 0%, #0891B2 100%);
    
    /* 背景色 */
    --background-color: #F1F5F9;
    --background-gradient: linear-gradient(180deg, #F8FAFC 0%, #E2E8F0 100%);
    --card-background: #FFFFFF;
    --sidebar-bg: linear-gradient(180deg, #1E293B 0%, #0F172A 100%);
    
    /* 文字颜色 */
    --text-primary: #1E293B;
    --text-secondary: #64748B;
    --text-light: #94A3B8;
    --text-white: #FFFFFF;
    
    /* 边框和阴影 */
    --border-color: #E2E8F0;
    --border-radius: 16px;
    --border-radius-sm: 10px;
    --border-radius-lg: 24px;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.12);
    --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.15);
    --shadow-primary: 0 4px 14px rgba(99, 102, 241, 0.4);
    --shadow-success: 0 4px 14px rgba(16, 185, 129, 0.4);
    --shadow-danger: 0 4px 14px rgba(239, 68, 68, 0.4);
}

/* ==================== 基础样式 ==================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background: var(--background-gradient);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.page {
    min-height: 100vh;
}

.hidden {
    display: none !important;
}

/* ==================== 登录页面 ==================== */
.login-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #6B8DD6 100%);
    background-size: 400% 400%;
    animation: gradientShift 15s ease infinite;
    padding: 20px;
    position: relative;
    overflow: hidden;
}

.login-container::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 50%);
    animation: floatBubble 20s linear infinite;
}

@keyframes gradientShift {
    0%, 100% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
}

@keyframes floatBubble {
    0% { transform: translate(0, 0) rotate(0deg); }
    100% { transform: translate(-50%, -50%) rotate(360deg); }
}

.login-card {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-radius: var(--border-radius-lg);
    padding: 48px 40px;
    width: 100%;
    max-width: 420px;
    box-shadow: var(--shadow-xl);
    position: relative;
    z-index: 1;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.login-header {
    text-align: center;
    margin-bottom: 36px;
}

.login-header h1 {
    font-size: 32px;
    margin-bottom: 8px;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 700;
}

.login-header p {
    color: var(--text-secondary);
    font-size: 14px;
    letter-spacing: 2px;
}

/* ==================== 表单样式 ==================== */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text-primary);
    font-size: 14px;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 14px 18px;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    font-size: 14px;
    transition: all 0.3s ease;
    background: #FAFBFC;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    background: #FFFFFF;
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

.form-group input::placeholder,
.form-group textarea::placeholder {
    color: var(--text-light);
}

.form-group textarea {
    resize: vertical;
    min-height: 100px;
}

.checkbox-group {
    display: flex;
    align-items: center;
}

.checkbox-group label {
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    margin-bottom: 0;
    font-weight: 500;
}

.checkbox-group input[type="checkbox"] {
    width: 20px;
    height: 20px;
    accent-color: var(--primary-color);
}

.form-actions {
    display: flex;
    gap: 12px;
    justify-content: flex-end;
    margin-top: 28px;
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
}

.form-row {
    display: flex;
    gap: 16px;
}

.form-row .form-group {
    flex: 1;
}

.radio-group {
    display: flex;
    gap: 24px;
    margin-top: 8px;
}

.radio-label {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    padding: 8px 16px;
    background: #F8FAFC;
    border-radius: var(--border-radius-sm);
    border: 2px solid transparent;
    transition: all 0.2s;
}

.radio-label:hover {
    background: #EEF2FF;
    border-color: var(--primary-light);
}

.radio-label input[type="radio"] {
    width: 18px;
    height: 18px;
    accent-color: var(--primary-color);
}

.required {
    color: var(--danger-color);
}

.form-hint {
    font-size: 12px;
    color: var(--text-secondary);
    margin-top: 6px;
    font-style: italic;
}

.text-muted {
    color: var(--text-secondary);
}

/* ==================== 按钮样式 ==================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 24px;
    border: none;
    border-radius: var(--border-radius-sm);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    white-space: nowrap;
}

.btn-primary {
    background: var(--primary-gradient);
    color: white;
    box-shadow: var(--shadow-primary);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.5);
}

.btn-secondary {
    background: linear-gradient(135deg, #64748B 0%, #475569 100%);
    color: white;
    box-shadow: 0 4px 14px rgba(100, 116, 139, 0.3);
}

.btn-secondary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(100, 116, 139, 0.4);
}

.btn-success {
    background: var(--success-gradient);
    color: white;
    box-shadow: var(--shadow-success);
}

.btn-success:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(16, 185, 129, 0.5);
}

.btn-danger {
    background: var(--danger-gradient);
    color: white;
    box-shadow: var(--shadow-danger);
}

.btn-danger:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(239, 68, 68, 0.5);
}

.btn-warning {
    background: var(--warning-gradient);
    color: white;
    box-shadow: 0 4px 14px rgba(245, 158, 11, 0.3);
}

.btn-warning:hover {
    transform: translateY(-2px);
}

.btn-info {
    background: var(--info-gradient);
    color: white;
    box-shadow: 0 4px 14px rgba(6, 182, 212, 0.3);
}

.btn-info:hover {
    transform: translateY(-2px);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--border-color);
    color: var(--text-secondary);
}

.btn-outline:hover {
    background: var(--background-color);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.btn-block {
    width: 100%;
}

.btn-sm {
    padding: 8px 16px;
    font-size: 13px;
}

.error-message {
    color: var(--danger-color);
    font-size: 14px;
    margin-top: 16px;
    text-align: center;
    padding: 12px;
    background: #FEF2F2;
    border-radius: var(--border-radius-sm);
}

/* ==================== 主界面布局 ==================== */
#main-page {
    display: flex;
    min-height: 100vh;
}

/* ==================== 侧边栏 ==================== */
.sidebar {
    width: 280px;
    background: var(--sidebar-bg);
    display: flex;
    flex-direction: column;
    position: fixed;
    height: 100vh;
    z-index: 100;
    box-shadow: 4px 0 20px rgba(0, 0, 0, 0.1);
}

.sidebar-header {
    padding: 28px 24px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.sidebar-header h2 {
    font-size: 22px;
    color: var(--text-white);
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 12px;
}

.sidebar-nav {
    flex: 1;
    padding: 20px 16px;
    overflow-y: auto;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 16px 20px;
    border-radius: var(--border-radius-sm);
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    margin-bottom: 6px;
    transition: all 0.3s ease;
    font-weight: 500;
}

.nav-item:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-white);
    transform: translateX(4px);
}

.nav-item.active {
    background: var(--primary-gradient);
    color: white;
    box-shadow: var(--shadow-primary);
}

.nav-item .icon {
    font-size: 22px;
    width: 28px;
    text-align: center;
}

.sidebar-footer {
    padding: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.sidebar-footer .btn {
    width: 100%;
    background: rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.8);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.sidebar-footer .btn:hover {
    background: rgba(255, 255, 255, 0.2);
    color: white;
}

/* ==================== 主内容区 ==================== */
.main-content {
    flex: 1;
    margin-left: 280px;
    padding: 32px;
    min-height: 100vh;
    background: var(--background-gradient);
}

.content-page {
    max-width: 1400px;
    margin: 0 auto;
}

.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 32px;
    padding-bottom: 20px;
    border-bottom: 2px solid var(--border-color);
}

.page-header h1 {
    font-size: 32px;
    color: var(--text-primary);
    font-weight: 700;
    position: relative;
}

.page-header h1::after {
    content: '';
    position: absolute;
    bottom: -22px;
    left: 0;
    width: 60px;
    height: 4px;
    background: var(--primary-gradient);
    border-radius: 2px;
}

/* ==================== 统计卡片 ==================== */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 24px;
    margin-bottom: 32px;
}

.stat-card {
    background: var(--card-background);
    border-radius: var(--border-radius);
    padding: 28px;
    display: flex;
    align-items: center;
    gap: 24px;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
    border: 1px solid rgba(0, 0, 0, 0.04);
    position: relative;
    overflow: hidden;
}

.stat-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-gradient);
}

.stat-card:nth-child(2)::before {
    background: var(--success-gradient);
}

.stat-card:nth-child(3)::before {
    background: var(--warning-gradient);
}

.stat-card:nth-child(4)::before {
    background: var(--info-gradient);
}

.stat-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.stat-icon {
    font-size: 48px;
    width: 80px;
    height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #EEF2FF 0%, #E0E7FF 100%);
    border-radius: var(--border-radius-sm);
}

.stat-card:nth-child(2) .stat-icon {
    background: linear-gradient(135deg, #D1FAE5 0%, #A7F3D0 100%);
}

.stat-card:nth-child(3) .stat-icon {
    background: linear-gradient(135deg, #FEF3C7 0%, #FDE68A 100%);
}

.stat-card:nth-child(4) .stat-icon {
    background: linear-gradient(135deg, #CFFAFE 0%, #A5F3FC 100%);
}

.stat-info h3 {
    font-size: 36px;
    color: var(--text-primary);
    margin-bottom: 4px;
    font-weight: 700;
}

.stat-info p {
    color: var(--text-secondary);
    font-size: 14px;
    font-weight: 500;
}

/* ==================== 快捷操作 ==================== */
.quick-actions {
    background: var(--card-background);
    border-radius: var(--border-radius);
    padding: 28px;
    box-shadow: var(--shadow);
}

.quick-actions h2 {
    font-size: 18px;
    margin-bottom: 20px;
    color: var(--text-primary);
    font-weight: 600;
}

.action-buttons {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

/* ==================== 表格容器 ==================== */
.table-container {
    background: var(--card-background);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    border: 1px solid rgba(0, 0, 0, 0.04);
}

.data-table {
    width: 100%;
    border-collapse: collapse;
}

.data-table th,
.data-table td {
    padding: 16px 20px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.data-table th {
    background: linear-gradient(180deg, #F8FAFC 0%, #F1F5F9 100%);
    font-weight: 700;
    color: var(--text-secondary);
    font-size: 12px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.data-table td {
    color: var(--text-primary);
    font-size: 14px;
}

.data-table tr:hover td {
    background: #F8FAFC;
}

.data-table .loading {
    text-align: center;
    color: var(--text-secondary);
    padding: 60px 40px;
    font-size: 15px;
}

.data-table .actions {
    display: flex;
    gap: 8px;
}

/* ==================== 词库管理页面美化 ==================== */

/* 小学词库 - 浅绿色 */
.library-row-elementary {
    background: linear-gradient(90deg, #ECFDF5 0%, #D1FAE5 30%, #FFFFFF 100%) !important;
    border-left: 4px solid #10B981;
}
.library-row-elementary:hover td {
    background: #D1FAE5 !important;
}
.library-row-elementary .library-name-cell {
    color: #047857;
    font-weight: 600;
}

/* 初中词库 - 浅橙色 */
.library-row-junior {
    background: linear-gradient(90deg, #FFFBEB 0%, #FEF3C7 30%, #FFFFFF 100%) !important;
    border-left: 4px solid #F59E0B;
}
.library-row-junior:hover td {
    background: #FEF3C7 !important;
}
.library-row-junior .library-name-cell {
    color: #B45309;
    font-weight: 600;
}

/* 高中词库 - 浅紫色 */
.library-row-senior {
    background: linear-gradient(90deg, #FAF5FF 0%, #F3E8FF 30%, #FFFFFF 100%) !important;
    border-left: 4px solid #A855F7;
}
.library-row-senior:hover td {
    background: #F3E8FF !important;
}
.library-row-senior .library-name-cell {
    color: #7C3AED;
    font-weight: 600;
}

/* 大学词库 - 浅蓝色 */
.library-row-college {
    background: linear-gradient(90deg, #EFF6FF 0%, #DBEAFE 30%, #FFFFFF 100%) !important;
    border-left: 4px solid #3B82F6;
}
.library-row-college:hover td {
    background: #DBEAFE !important;
}
.library-row-college .library-name-cell {
    color: #1D4ED8;
    font-weight: 600;
}

/* 分类栏目行样式 */
.library-category-row {
    background: linear-gradient(90deg, #F8FAFC 0%, #F1F5F9 50%, #FFFFFF 100%) !important;
    border-left: 4px solid #64748B;
}
.library-category-row td {
    font-weight: 600;
    color: #334155;
}

/* 词库操作按钮组 */
.library-actions {
    display: flex;
    gap: 8px;
    align-items: center;
    justify-content: flex-end;
}

.library-actions .btn {
    padding: 8px 14px;
    font-size: 12px;
    border-radius: 8px;
    font-weight: 600;
    min-width: 56px;
    transition: all 0.25s ease;
}

.library-actions .btn-words {
    background: linear-gradient(135deg, #3B82F6 0%, #2563EB 100%);
    color: white;
    border: none;
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.3);
}
.library-actions .btn-words:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.4);
}

.library-actions .btn-edit {
    background: linear-gradient(135deg, #10B981 0%, #059669 100%);
    color: white;
    border: none;
    box-shadow: 0 2px 8px rgba(16, 185, 129, 0.3);
}
.library-actions .btn-edit:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(16, 185, 129, 0.4);
}

.library-actions .btn-delete {
    background: linear-gradient(135deg, #EF4444 0%, #DC2626 100%);
    color: white;
    border: none;
    box-shadow: 0 2px 8px rgba(239, 68, 68, 0.3);
}
.library-actions .btn-delete:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.4);
}

/* 词库类型标签 */
.library-type-badge {
    display: inline-flex;
    align-items: center;
    padding: 5px 12px;
    border-radius: 20px;
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.library-type-badge.frequency {
    background: linear-gradient(135deg, #FEF3C7 0%, #FDE68A 100%);
    color: #B45309;
}

.library-type-badge.normal {
    background: linear-gradient(135deg, #DBEAFE 0%, #BFDBFE 100%);
    color: #1D4ED8;
}

.library-type-badge.category {
    background: linear-gradient(135deg, #E2E8F0 0%, #CBD5E1 100%);
    color: #475569;
}

/* 付费标签 */
.library-price-badge {
    display: inline-flex;
    align-items: center;
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 600;
}

.library-price-badge.free {
    background: #D1FAE5;
    color: #047857;
}

.library-price-badge.paid {
    background: #FEF3C7;
    color: #B45309;
}

/* 状态标签 */
.library-status-badge {
    display: inline-flex;
    align-items: center;
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 600;
}

.library-status-badge.active {
    background: #D1FAE5;
    color: #047857;
}

.library-status-badge.inactive {
    background: #FEE2E2;
    color: #B91C1C;
}

/* 单词数量 */
.word-count-cell {
    font-weight: 700;
    color: #3B82F6;
    font-size: 15px;
}

.word-count-cell.zero {
    color: #94A3B8;
    font-weight: 400;
}

/* 排序按钮 */
.sort-buttons {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.sort-buttons .btn-sort {
    padding: 4px 8px;
    font-size: 10px;
    background: #F1F5F9;
    border: 1px solid #E2E8F0;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s;
    color: #64748B;
}

.sort-buttons .btn-sort:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* 版本号 */
.version-badge {
    display: inline-flex;
    align-items: center;
    padding: 4px 10px;
    background: #F1F5F9;
    border-radius: 8px;
    font-size: 12px;
    color: #64748B;
    font-family: 'Monaco', 'Consolas', monospace;
    font-weight: 600;
}

/* ==================== 状态标签 ==================== */
.status-badge {
    display: inline-flex;
    align-items: center;
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 12px;
    font-weight: 600;
}

.status-badge.active {
    background: linear-gradient(135deg, #D1FAE5 0%, #A7F3D0 100%);
    color: #047857;
}

.status-badge.inactive {
    background: linear-gradient(135deg, #FEE2E2 0%, #FECACA 100%);
    color: #B91C1C;
}

.status-badge.pinned {
    background: linear-gradient(135deg, #FEF3C7 0%, #FDE68A 100%);
    color: #B45309;
}

.badge {
    display: inline-flex;
    align-items: center;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 600;
}

.badge-success {
    background: #D1FAE5;
    color: #047857;
}

.badge-warning {
    background: #FEF3C7;
    color: #B45309;
}

.badge-secondary {
    background: #E2E8F0;
    color: #475569;
}

.badge-info {
    background: #DBEAFE;
    color: #1D4ED8;
}

.badge-primary {
    background: #EDE9FE;
    color: #7C3AED;
}

/* ==================== 上传区域 ==================== */
.upload-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 28px;
}

.upload-card,
.preview-card {
    background: var(--card-background);
    border-radius: var(--border-radius);
    padding: 28px;
    box-shadow: var(--shadow);
}

.upload-card h3,
.preview-card h3 {
    margin-bottom: 8px;
    font-size: 18px;
    font-weight: 700;
    color: var(--text-primary);
}

.upload-hint {
    color: var(--text-secondary);
    font-size: 14px;
    margin-bottom: 24px;
}

.file-upload-area {
    border: 3px dashed var(--border-color);
    border-radius: var(--border-radius-sm);
    padding: 48px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    background: #FAFBFC;
}

.file-upload-area:hover,
.file-upload-area.dragover {
    border-color: var(--primary-color);
    background: linear-gradient(135deg, #EEF2FF 0%, #E0E7FF 100%);
    transform: scale(1.01);
}

.file-upload-content {
    color: var(--text-secondary);
}

.upload-icon {
    font-size: 56px;
    display: block;
    margin-bottom: 16px;
}

.file-name {
    color: var(--primary-color);
    font-weight: 600;
    margin-top: 12px;
}

/* 分频版上传 */
.frequency-upload-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    margin-bottom: 20px;
}

.frequency-upload-item {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.frequency-label {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 18px;
    border-radius: var(--border-radius-sm);
    font-weight: 700;
    font-size: 14px;
}

.frequency-label .freq-icon {
    font-size: 20px;
}

.frequency-label.high-freq {
    background: linear-gradient(135deg, #FEE2E2 0%, #FECACA 100%);
    color: #B91C1C;
}

.frequency-label.mid-freq {
    background: linear-gradient(135deg, #FEF3C7 0%, #FDE68A 100%);
    color: #B45309;
}

.frequency-label.low-freq {
    background: linear-gradient(135deg, #D1FAE5 0%, #A7F3D0 100%);
    color: #047857;
}

.frequency-upload-item .file-upload-area {
    padding: 32px;
    min-height: 120px;
}

.preview-table-container {
    max-height: 400px;
    overflow-y: auto;
    margin-top: 16px;
    border-radius: var(--border-radius-sm);
}

#preview-stats {
    padding: 16px;
    background: linear-gradient(135deg, #F8FAFC 0%, #F1F5F9 100%);
    border-radius: var(--border-radius-sm);
    margin-bottom: 16px;
    font-weight: 500;
}

/* ==================== 设置页面 ==================== */
.settings-container {
    max-width: 700px;
    display: flex;
    flex-direction: column;
    gap: 28px;
}

.settings-card {
    background: var(--card-background);
    border-radius: var(--border-radius);
    padding: 28px;
    box-shadow: var(--shadow);
}

.settings-card h3 {
    margin-bottom: 8px;
    font-size: 18px;
    font-weight: 700;
    color: var(--text-primary);
}

.settings-hint {
    color: var(--text-secondary);
    font-size: 14px;
    margin-bottom: 24px;
}

.settings-switches {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.switch-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 18px 20px;
    background: linear-gradient(135deg, #F8FAFC 0%, #F1F5F9 100%);
    border-radius: var(--border-radius-sm);
    border: 1px solid var(--border-color);
}

.switch-info label {
    display: block;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
    font-size: 15px;
}

.switch-desc {
    font-size: 13px;
    color: var(--text-secondary);
}

/* 开关按钮 */
.switch {
    position: relative;
    display: inline-block;
    width: 56px;
    height: 30px;
    flex-shrink: 0;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #CBD5E1;
    transition: 0.3s;
}

.slider:before {
    position: absolute;
    content: "";
    height: 24px;
    width: 24px;
    left: 3px;
    bottom: 3px;
    background-color: white;
    transition: 0.3s;
    box-shadow: 0 2px 6px rgba(0,0,0,0.2);
}

input:checked + .slider {
    background: var(--primary-gradient);
}

input:checked + .slider:before {
    transform: translateX(26px);
}

.slider.round {
    border-radius: 30px;
}

.slider.round:before {
    border-radius: 50%;
}

/* ==================== 模态框 ==================== */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(15, 23, 42, 0.6);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    padding: 20px;
    animation: fadeIn 0.2s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.modal-content {
    background: white;
    border-radius: var(--border-radius);
    width: 100%;
    max-width: 540px;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: var(--shadow-xl);
    animation: slideUp 0.3s ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.modal-large {
    max-width: 750px;
}

.modal-xlarge {
    max-width: 1100px;
    width: 95%;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 24px 28px;
    border-bottom: 2px solid var(--border-color);
    background: linear-gradient(180deg, #FFFFFF 0%, #F8FAFC 100%);
}

.modal-header h2 {
    font-size: 22px;
    font-weight: 700;
    color: var(--text-primary);
}

.modal-close {
    background: none;
    border: none;
    font-size: 32px;
    color: var(--text-secondary);
    cursor: pointer;
    line-height: 1;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: all 0.2s;
}

.modal-close:hover {
    background: #FEE2E2;
    color: var(--danger-color);
}

.modal-content form {
    padding: 28px;
}

.modal-body {
    padding: 24px 28px;
    max-height: 65vh;
    overflow-y: auto;
}

/* ==================== Toast 消息 ==================== */
.toast {
    position: fixed;
    bottom: 32px;
    right: 32px;
    padding: 18px 28px;
    background: var(--text-primary);
    color: white;
    border-radius: var(--border-radius-sm);
    box-shadow: var(--shadow-xl);
    z-index: 2000;
    animation: slideIn 0.4s ease;
    font-weight: 500;
    font-size: 15px;
}

.toast.success {
    background: var(--success-gradient);
}

.toast.error {
    background: var(--danger-gradient);
}

@keyframes slideIn {
    from {
        transform: translateX(120%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* ==================== 搜索栏 ==================== */
.search-bar {
    display: flex;
    gap: 12px;
    margin-bottom: 24px;
    background: var(--card-background);
    padding: 20px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.search-bar input {
    flex: 1;
    padding: 14px 20px;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    font-size: 15px;
    transition: all 0.3s;
}

.search-bar input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

/* ==================== 分页 ==================== */
.pagination {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    margin-top: 24px;
    padding: 20px;
}

.pagination-info {
    color: var(--text-secondary);
    font-size: 14px;
    margin-right: 16px;
    font-weight: 500;
}

/* ==================== 用户详情 ==================== */
.user-info-card,
.user-purchases-card,
.user-trials-card {
    background: linear-gradient(135deg, #F8FAFC 0%, #F1F5F9 100%);
    border-radius: var(--border-radius-sm);
    padding: 24px;
    margin-bottom: 20px;
    border: 1px solid var(--border-color);
}

.user-info-card h3,
.user-purchases-card h3,
.user-trials-card h3 {
    font-size: 16px;
    margin-bottom: 16px;
    color: var(--text-primary);
    font-weight: 700;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 16px;
}

.info-item {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.info-item label {
    font-size: 12px;
    color: var(--text-secondary);
    font-weight: 600;
    text-transform: uppercase;
}

.info-item span {
    font-size: 14px;
    color: var(--text-primary);
    word-break: break-all;
    font-weight: 500;
}

.data-table.mini {
    font-size: 13px;
}

.data-table.mini th,
.data-table.mini td {
    padding: 12px 14px;
}

.empty {
    text-align: center;
    color: var(--text-secondary);
    padding: 24px !important;
    font-style: italic;
}

.header-actions {
    display: flex;
    gap: 12px;
    align-items: center;
}

.uid-cell {
    max-width: 150px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    font-family: 'Monaco', 'Consolas', monospace;
    font-size: 12px;
    color: var(--text-secondary);
}

/* ==================== 皮肤选择器 ==================== */
.skin-selector {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    margin-top: 16px;
}

.skin-option {
    position: relative;
    cursor: pointer;
    border: 3px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    padding: 14px;
    text-align: center;
    transition: all 0.3s ease;
    background: white;
}

.skin-option:hover {
    border-color: var(--primary-color);
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.skin-option.active {
    border-color: var(--primary-color);
    background: linear-gradient(135deg, #EEF2FF 0%, #E0E7FF 100%);
}

.skin-option.active .skin-check {
    display: flex;
}

.skin-preview {
    width: 100%;
    height: 80px;
    border-radius: 8px;
    overflow: hidden;
    position: relative;
    margin-bottom: 10px;
}

.skin-name {
    font-weight: 700;
    font-size: 14px;
    color: var(--text-primary);
    margin-bottom: 2px;
}

.skin-desc {
    font-size: 12px;
    color: var(--text-secondary);
}

.skin-check {
    display: none;
    position: absolute;
    top: 10px;
    right: 10px;
    width: 26px;
    height: 26px;
    background: var(--primary-gradient);
    color: white;
    border-radius: 50%;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    font-weight: bold;
    box-shadow: 0 2px 8px rgba(99, 102, 241, 0.4);
}

.skin-light-blue {
    background: linear-gradient(180deg, #E8F4FC 0%, #FFFFFF 100%);
}

.skin-textured-blue {
    background: linear-gradient(135deg, #1a237e 0%, #3949ab 50%, #5c6bc0 100%);
}

.skin-textured-blue .skin-light-effect {
    position: absolute;
    top: -20px;
    right: -20px;
    width: 60px;
    height: 60px;
    background: radial-gradient(circle, rgba(255,255,255,0.3) 0%, transparent 70%);
    border-radius: 50%;
}

.skin-green-willow {
    background: linear-gradient(180deg, #E8F5E9 0%, #C8E6C9 50%, #A5D6A7 100%);
}

.skin-custom {
    background: #f5f5f5;
    border: 2px dashed #ccc;
    display: flex;
    align-items: center;
    justify-content: center;
}

.skin-upload-placeholder {
    text-align: center;
    color: var(--text-secondary);
}

.skin-upload-placeholder .upload-icon {
    font-size: 28px;
}

.skin-image-preview {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-size: cover;
    background-position: center;
    border-radius: 8px;
}

.skin-change-btn {
    position: absolute;
    bottom: 6px;
    right: 6px;
    background: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 4px 10px;
    border-radius: 6px;
    font-size: 11px;
    cursor: pointer;
    transition: background 0.2s;
}

.skin-change-btn:hover {
    background: rgba(0, 0, 0, 0.9);
}

.skin-custom.has-image {
    border: none;
}

.skin-custom.has-image .skin-upload-placeholder {
    display: none;
}

.auto-refresh-status {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: var(--text-secondary);
    padding: 10px 16px;
    background: linear-gradient(135deg, #D1FAE5 0%, #A7F3D0 100%);
    border-radius: var(--border-radius-sm);
    font-weight: 500;
}

/* ==================== 清空单词区域 ==================== */
.clear-words-section {
    display: none;
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 18px 20px;
    margin: 16px 0;
    background: linear-gradient(135deg, #FEF2F2 0%, #FEE2E2 100%);
    border: 2px solid #FECACA;
    border-radius: var(--border-radius-sm);
    animation: fadeIn 0.3s ease;
}

.clear-words-info {
    display: flex;
    align-items: center;
    gap: 10px;
    flex: 1;
}

.clear-words-info .info-icon {
    font-size: 20px;
}

.clear-words-info span:last-child {
    color: #B91C1C;
    font-size: 14px;
    font-weight: 600;
}

.btn-clear-words {
    white-space: nowrap;
    padding: 12px 24px;
    font-size: 14px;
    font-weight: 700;
}

/* ==================== 单词管理模态框 ==================== */
.modal-xlarge .modal-body {
    padding: 24px 28px;
    max-height: 75vh;
    overflow-y: auto;
}

.words-toolbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    margin-bottom: 24px;
    flex-wrap: wrap;
}

.words-toolbar .search-box {
    display: flex;
    gap: 10px;
    flex: 1;
    min-width: 320px;
}

.words-toolbar .search-box input {
    flex: 1;
    padding: 12px 18px;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    font-size: 14px;
    transition: all 0.3s;
}

.words-toolbar .search-box input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

.words-toolbar .toolbar-actions {
    display: flex;
    gap: 10px;
}

.words-table-container {
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    overflow: hidden;
    max-height: 50vh;
    overflow-y: auto;
}

.words-table {
    width: 100%;
    font-size: 14px;
}

.words-table th {
    position: sticky;
    top: 0;
    background: linear-gradient(180deg, #F8FAFC 0%, #F1F5F9 100%);
    z-index: 10;
    font-weight: 700;
}

.words-table td.phonetic {
    color: #64748B;
    font-size: 13px;
}

.words-table td.meaning {
    max-width: 200px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.words-pagination {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 20px;
    padding-top: 20px;
    border-top: 2px solid var(--border-color);
}

.words-pagination #words-pagination-info {
    color: var(--text-secondary);
    font-size: 14px;
    font-weight: 500;
}

.words-pagination #words-pagination-buttons {
    display: flex;
    gap: 6px;
    align-items: center;
}

.pagination-ellipsis {
    padding: 0 8px;
    color: var(--text-secondary);
}

.btn-icon {
    background: linear-gradient(135deg, #F8FAFC 0%, #E2E8F0 100%);
    border: 2px solid var(--border-color);
    border-radius: 6px;
    padding: 4px 8px;
    cursor: pointer;
    font-size: 10px;
    color: var(--text-secondary);
    transition: all 0.2s;
}

.btn-icon:hover {
    background: var(--primary-gradient);
    color: white;
    border-color: var(--primary-color);
}

/* ==================== 响应式设计 ==================== */
@media (max-width: 1024px) {
    .upload-container {
        grid-template-columns: 1fr;
    }
    
    .frequency-upload-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .sidebar {
        width: 100%;
        height: auto;
        position: relative;
    }
    
    .main-content {
        margin-left: 0;
        padding: 20px;
    }
    
    #main-page {
        flex-direction: column;
    }
    
    .sidebar-nav {
        display: flex;
        overflow-x: auto;
        padding: 12px;
    }
    
    .nav-item {
        flex-shrink: 0;
    }
    
    .page-header {
        flex-direction: column;
        gap: 16px;
        align-items: flex-start;
    }
    
    .skin-selector {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .modal-xlarge {
        width: 98%;
    }
    
    .words-toolbar {
        flex-direction: column;
        align-items: stretch;
    }
    
    .words-toolbar .search-box {
        min-width: auto;
    }
    
    .clear-words-section {
        flex-direction: column;
        text-align: center;
    }
}

/* ==================== 动画效果 ==================== */
@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.02); }
}

.stat-card:hover .stat-icon {
    animation: pulse 0.6s ease;
}

/* ==================== 滚动条美化 ==================== */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: #F1F5F9;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: #CBD5E1;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: #94A3B8;
}

/* ==================== 顶级词库行样式 ==================== */
.top-level-row {
    background-color: #FAFBFC;
}

.sub-level-row td:nth-child(2) {
    color: var(--text-secondary);
}