/* ============================================
   基础样式 & 变量
   ============================================ */
:root {
    /* 颜色系统 */
    --color-bg: #F6F8FB;
    --color-card: #FFFFFF;
    --color-primary: #2563EB;
    --color-success: #16A34A;
    --color-warning: #F97316;
    --color-danger: #DC2626;
    --color-border: #E5E7EB;
    --color-text: #111827;
    --color-text-secondary: #6B7280;
    
    /* 圆角 */
    --radius-card: 8px;
    --radius-button: 6px;
    
    /* 间距 */
    --container-width: 1200px;
    --spacing-xs: 8px;
    --spacing-sm: 16px;
    --spacing-md: 24px;
    --spacing-lg: 32px;
    --spacing-xl: 48px;
    
    /* 字体 */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    
    /* 阴影 */
    --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);
}

/* ============================================
   重置样式
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-sans);
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color 0.2s ease;
}

a:hover {
    color: #1e40af;
}

ul, ol {
    list-style: none;
}

button {
    font-family: inherit;
    cursor: pointer;
}

/* ============================================
   布局工具类
   ============================================ */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ============================================
   按钮样式
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 24px;
    border: none;
    border-radius: var(--radius-button);
    font-size: 14px;
    font-weight: 600;
    text-align: center;
    transition: all 0.2s ease;
    cursor: pointer;
    text-decoration: none;
}

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

.btn-primary:hover {
    background-color: #1e40af;
    color: white;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: transparent;
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

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

.btn-deal {
    background-color: var(--color-warning);
    color: white;
    width: 100%;
}

.btn-deal:hover {
    background-color: #ea580c;
    color: white;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

/* ============================================
   网站头部
   ============================================ */
.site-header {
    background-color: white;
    border-bottom: 1px solid var(--color-border);
    padding: var(--spacing-sm) 0;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

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

.site-branding .logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 20px;
    font-weight: 700;
    color: var(--color-text);
    text-decoration: none;
}

.logo-icon {
    font-size: 28px;
}

.main-navigation .nav-menu {
    display: flex;
    gap: var(--spacing-lg);
}

.main-navigation .nav-menu a {
    color: var(--color-text);
    font-weight: 500;
    font-size: 15px;
}

.main-navigation .nav-menu a:hover {
    color: var(--color-primary);
}

.header-actions .search-toggle {
    background: none;
    border: none;
    padding: 8px;
    color: var(--color-text);
    display: flex;
    align-items: center;
}

.header-actions .search-toggle:hover {
    color: var(--color-primary);
}

/* ============================================
   网站底部
   ============================================ */
.site-footer {
    background-color: white;
    border-top: 1px solid var(--color-border);
    margin-top: var(--spacing-xl);
    padding: var(--spacing-xl) 0 var(--spacing-md);
}

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

.footer-section h3 {
    font-size: 18px;
    margin-bottom: var(--spacing-sm);
}

.footer-section h4 {
    font-size: 16px;
    margin-bottom: var(--spacing-sm);
    font-weight: 600;
}

.footer-section p {
    color: var(--color-text-secondary);
    font-size: 14px;
}

.footer-section ul li {
    margin-bottom: 8px;
}

.footer-section ul li a {
    color: var(--color-text-secondary);
    font-size: 14px;
}

.footer-section ul li a:hover {
    color: var(--color-primary);
}

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

.footer-bottom p {
    color: var(--color-text-secondary);
    font-size: 14px;
}

/* ============================================
   响应式设计 - 平板
   ============================================ */
@media (max-width: 768px) {
    .header-content {
        flex-wrap: wrap;
    }
    
    .main-navigation {
        order: 3;
        width: 100%;
        margin-top: var(--spacing-sm);
    }
    
    .main-navigation .nav-menu {
        gap: var(--spacing-md);
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }
    
    .footer-content {
        grid-template-columns: 1fr 1fr;
    }
}

/* ============================================
   响应式设计 - 手机
   ============================================ */
@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .main-navigation .nav-menu {
        gap: var(--spacing-sm);
        font-size: 14px;
    }
}