/* 基础重置和变量 */
:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --accent-color: #4facfe;
    --success-color: #56ab2f;
    --warning-color: #f7971e;
    --error-color: #ff416c;
    --info-color: #4facfe;
    
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-dark: #1a202c;
    --bg-sidebar: #2d3748;
    
    --text-primary: #2d3748;
    --text-secondary: #718096;
    --text-light: #a0aec0;
    --text-white: #ffffff;
    
    --border-color: #e2e8f0;
    --border-radius: 12px;
    --border-radius-lg: 16px;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    
    --sidebar-width: 280px;
    --topbar-height: 70px;
    
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

/* 侧边栏样式 */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: var(--sidebar-width);
    height: 100vh;
    background: linear-gradient(135deg, var(--bg-sidebar) 0%, #4a5568 100%);
    color: var(--text-white);
    z-index: 1000;
    transform: translateX(0);
    transition: var(--transition);
    box-shadow: var(--shadow-lg);
}

.sidebar-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1.5rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.25rem;
    font-weight: 700;
}

.logo i {
    font-size: 1.5rem;
    color: var(--accent-color);
}

.sidebar-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-white);
    font-size: 1.25rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 6px;
    transition: var(--transition);
}

.sidebar-toggle:hover {
    background: rgba(255, 255, 255, 0.1);
}

.sidebar-menu {
    padding: 1rem 0;
    flex: 1;
}

.menu-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.875rem 1.5rem;
    color: var(--text-light);
    text-decoration: none;
    transition: var(--transition);
    border-left: 3px solid transparent;
}

.menu-item:hover {
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-white);
}

.menu-item.active {
    background: rgba(79, 172, 254, 0.1);
    color: var(--text-white);
    border-left-color: var(--accent-color);
}

.menu-item i {
    font-size: 1.125rem;
    width: 1.25rem;
}

.sidebar-footer {
    padding: 1.5rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.user-info {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--text-light);
}

/* 主内容区域 */
.main-content {
    margin-left: var(--sidebar-width);
    min-height: 100vh;
    transition: var(--transition);
}

/* 顶部导航栏 */
.topbar {
    height: var(--topbar-height);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow);
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.25rem;
    color: var(--text-primary);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 6px;
    transition: var(--transition);
}

.menu-toggle:hover {
    background: var(--bg-primary);
}

.topbar-title h1 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.topbar-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.action-btn {
    background: none;
    border: none;
    font-size: 1.125rem;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 6px;
    transition: var(--transition);
}

.action-btn:hover {
    background: var(--bg-primary);
    color: var(--text-primary);
}

.status-indicator {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.status-indicator i {
    color: var(--success-color);
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

/* 内容包装器 */
.content-wrapper {
    padding: 2rem;
}

.content-section {
    display: none;
}

.content-section.active {
    display: block;
}

/* 统计卡片网格 */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--bg-secondary);
    border-radius: var(--border-radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.stat-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.stat-card {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
}

.stat-icon {
    width: 3rem;
    height: 3rem;
    border-radius: var(--border-radius);
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-white);
    font-size: 1.25rem;
    flex-shrink: 0;
}

.stat-content {
    flex: 1;
}

.stat-content h3 {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.stat-change {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.stat-change.positive {
    color: var(--success-color);
}

.stat-change.negative {
    color: var(--error-color);
}

/* 操作按钮网格 */
.actions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.action-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.75rem;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    color: var(--text-primary);
}

.action-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    color: var(--text-white);
    border-color: transparent;
}

.action-card i {
    font-size: 1.5rem;
}

.action-card span {
    font-weight: 500;
}

/* 空状态 */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.empty-state p {
    font-size: 1.125rem;
}

/* 响应式设计 */
@media (max-width: 1024px) {
    .stats-grid {
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    }
    
    .actions-grid {
        grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    }
}

@media (max-width: 768px) {
    :root {
        --sidebar-width: 100%;
    }
    
    .sidebar {
        transform: translateX(-100%);
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    .main-content {
        margin-left: 0;
    }
    
    .menu-toggle,
    .sidebar-toggle {
        display: block;
    }
    
    .topbar {
        padding: 0 1rem;
    }
    
    .content-wrapper {
        padding: 1rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .actions-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 0.75rem;
    }
    
    .stat-card {
        padding: 1rem;
    }
    
    .action-card {
        padding: 1rem;
    }
    
    .stat-value {
        font-size: 1.5rem;
    }
}

@media (max-width: 480px) {
    .actions-grid {
        grid-template-columns: 1fr;
    }
    
    .topbar-title h1 {
        font-size: 1.25rem;
    }
    
    .stat-card {
        flex-direction: column;
        text-align: center;
        gap: 0.75rem;
    }
    
    .stat-icon {
        align-self: center;
    }
}