/* Tailwind CSS CDN */
@import url('https://cdn.jsdelivr.net/npm/tailwindcss@2.2.19/dist/tailwind.min.css');

/* Custom CSS Variables */
:root {
    /* Primary Colors - 蓝色系 */
    --primary-500: #1E90FF;
    --primary-600: #4169E1;
    --primary-700: #0066CC;
    
    /* Background Colors */
    --bg-primary: #FFFFFF;
    --bg-secondary: #F5F7FA;
    --bg-tertiary: #E8ECEF;
    
    /* Text Colors */
    --text-primary: #2C3E50;
    --text-secondary: #5A6C7D;
    --text-tertiary: #8492A6;
    
    /* Functional Colors */
    --color-success: #27AE60;
    --color-error: #E74C3C;
    --color-warning: #F39C12;
    
    /* Typography */
    --font-family: 'PingFang-SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 12px;
    --font-size-sm: 14px;
    --font-size-base: 16px;
    --font-size-lg: 18px;
    --font-size-xl: 24px;
    --font-size-2xl: 32px;
    
    /* Spacing */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-2xl: 48px;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* Navbar */
.navbar {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--bg-tertiary);
    box-shadow: var(--shadow-sm);
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.logo a {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--primary-500);
    text-decoration: none;
    transition: color 0.3s ease;
}

.logo a:hover {
    color: var(--primary-600);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-xl);
}

.nav-menu a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-500);
    transition: width 0.3s ease;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--primary-500);
}

.nav-menu a:hover::after,
.nav-menu a.active::after {
    width: 100%;
}

.search-box {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.search-box input {
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--bg-tertiary);
    border-radius: var(--radius-md);
    outline: none;
    transition: border-color 0.3s ease;
    width: 200px;
}

.search-box input:focus {
    border-color: var(--primary-500);
}

.search-box button {
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--primary-500);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: background 0.3s ease;
}

.search-box button:hover {
    background: var(--primary-600);
}

/* Section Title */
.section-title {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xl);
    text-align: center;
}

/* Card Styles */
.card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
}

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

/* Button Styles */
.btn {
    display: inline-block;
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-base);
    font-weight: 500;
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all 0.3s ease;
    cursor: pointer;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-500), var(--primary-600));
    color: white;
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-600), var(--primary-700));
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* Footer */
.footer {
    background: var(--bg-secondary);
    padding: var(--spacing-2xl) 0;
    margin-top: var(--spacing-2xl);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-2xl);
    margin-bottom: var(--spacing-xl);
}

.footer-brand h3 {
    font-size: var(--font-size-xl);
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.footer-brand p {
    color: var(--text-secondary);
}

.footer-links h4,
.footer-social h4 {
    font-size: var(--font-size-lg);
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.footer-links ul {
    list-style: none;
}

.footer-links li {
    margin-bottom: var(--spacing-sm);
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-links a:hover {
    color: var(--primary-500);
}

.social-links {
    display: flex;
    gap: var(--spacing-md);
}

.social-link {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease;
}

.social-link:hover {
    color: var(--primary-500);
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--bg-tertiary);
    color: var(--text-tertiary);
}

/* Responsive Design */
@media (max-width: 768px) {
    .navbar .container {
        flex-direction: column;
        height: auto;
        padding: var(--spacing-md);
    }
    
    .nav-menu {
        margin: var(--spacing-md) 0;
    }
    
    .search-box {
        width: 100%;
    }
    
    .search-box input {
        flex: 1;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }
}