/* CSS 重置和基础样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* 主要颜色 */
    --primary-color: #3b82f6;
    --primary-light: #60a5fa;
    --primary-dark: #1d4ed8;
    --secondary-color: #8b5cf6;
    --accent-color: #f59e0b;
    
    /* 背景色 */
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --bg-card: #1e293b;
    
    /* 文字颜色 */
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #64748b;
    
    /* 边框和阴影 */
    --border-color: #334155;
    --shadow-light: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-medium: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-heavy: 0 20px 25px rgba(0, 0, 0, 0.15);
    --shadow-glow: 0 0 30px rgba(59, 130, 246, 0.15);
    
    /* 渐变 */
    --gradient-primary: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    --gradient-accent: linear-gradient(135deg, var(--accent-color), #ef4444);
    --gradient-bg: linear-gradient(135deg, var(--bg-primary), var(--bg-secondary));
    
    /* 间距 */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* 字体大小 */
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;
    --text-4xl: 2.25rem;
    --text-5xl: 3rem;
    
    /* 边界半径 */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* 过渡 */
    --transition-fast: 150ms ease-in-out;
    --transition-medium: 300ms ease-in-out;
    --transition-slow: 500ms ease-in-out;
    
    /* 断点 */
    --mobile: 768px;
    --tablet: 1024px;
    --desktop: 1280px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f8f9fa;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 头部 */
.header {
    background: white;
    border-bottom: 1px solid #e9ecef;
    padding: 20px 0;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand {
    font-size: 24px;
    font-weight: bold;
    color: #333;
    text-decoration: none;
}

.nav-brand i {
    color: #007bff;
    margin-right: 8px;
}

/* Hero区域 */
.hero {
    background: white;
    padding: 60px 0;
    text-align: center;
}

.hero-title {
    font-size: 42px;
    font-weight: bold;
    margin-bottom: 16px;
    color: #333;
}

.hero-description {
    font-size: 18px;
    color: #666;
    margin-bottom: 40px;
}

/* 分类导航 */
.categories {
    background: white;
    padding: 40px 0;
}

.categories-nav {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 40px;
    flex-wrap: wrap;
}

.category-nav-item {
    padding: 12px 24px;
    background: #f8f9fa;
    border: 1px solid #dee2e6;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    font-weight: 500;
    color: #666;
}

.category-nav-item:hover {
    background: #e9ecef;
    border-color: #007bff;
}

.category-nav-item.active {
    background: #007bff;
    color: white;
    border-color: #007bff;
}

/* 工具展示区域 */
.tools-display {
    background: white;
}

.tools-title {
    text-align: center;
    font-size: 28px;
    font-weight: bold;
    margin-bottom: 30px;
    color: #333;
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
    margin-bottom: 40px;
}

.tool-card {
    background: white;
    border: 1px solid #e9ecef;
    border-radius: 12px;
    padding: 24px;
    transition: all 0.2s ease;
    text-decoration: none;
    color: inherit;
    display: block;
}

.tool-card:hover {
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    transform: translateY(-2px);
    text-decoration: none;
    color: inherit;
    border-color: #007bff;
}

.tool-header {
    display: flex;
    align-items: center;
    margin-bottom: 16px;
}

.tool-icon {
    width: 48px;
    height: 48px;
    background: #007bff;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
    font-size: 16px;
    margin-right: 16px;
}

.tool-name {
    font-size: 20px;
    font-weight: bold;
    color: #333;
}

.tool-description {
    color: #666;
    font-size: 14px;
    line-height: 1.5;
    margin-bottom: 16px;
}

.tool-link {
    display: inline-flex;
    align-items: center;
    color: #007bff;
    font-size: 14px;
    font-weight: 500;
}

.tool-link i {
    margin-left: 4px;
    font-size: 12px;
}

/* 页脚 */
.footer {
    background: #343a40;
    color: white;
    padding: 40px 0 20px;
    margin-top: 60px;
}

.footer-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    margin-bottom: 30px;
}

.footer-brand {
    font-size: 20px;
    font-weight: bold;
    margin-bottom: 10px;
}

.footer-brand i {
    color: #007bff;
    margin-right: 8px;
}

.footer-text {
    color: #adb5bd;
    margin-bottom: 20px;
}

.footer-links h4 {
    margin-bottom: 15px;
    color: white;
}

.footer-links a {
    color: #adb5bd;
    text-decoration: none;
    display: block;
    margin-bottom: 8px;
    transition: color 0.2s ease;
}

.footer-links a:hover {
    color: #007bff;
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid #495057;
    color: #adb5bd;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }
    
    .hero-title {
        font-size: 32px;
    }
    
    .hero-description {
        font-size: 16px;
    }
    
    .categories-nav {
        gap: 10px;
    }
    
    .category-nav-item {
        padding: 10px 16px;
        font-size: 14px;
    }
    
    .tools-grid {
        grid-template-columns: 1fr;
        gap: 15px;
    }
    
    .tool-card {
        padding: 20px;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: 20px;
    }
}

@media (max-width: 480px) {
    .categories-nav {
        justify-content: flex-start;
        overflow-x: auto;
        padding-bottom: 10px;
    }
    
    .category-nav-item {
        white-space: nowrap;
        flex-shrink: 0;
    }
}