/**
 * CRCAI Global Styles
 * 全局样式表 - 变量、重置、页眉、页脚
 * 
 * 目录:
 * 1. CSS变量
 * 2. Reset & Base
 * 3. 工具类
 * 4. 主导航 Header
 * 5. 页脚 Footer
 * 6. 通用组件
 * 7. 响应式（全局）
 */

/* ==========================================================================
   1. CSS变量
   ========================================================================== */
:root {
    /* 企业级配色方案 */
    --primary-blue: #0068B5;
    --deep-blue: #003C71;
    --tech-blue: #0080FF;
    --light-blue: #E6F2FF;
    
    /* 专业灰色系 */
    --gray-100: #F8F9FA;
    --gray-200: #E9ECEF;
    --gray-300: #DEE2E6;
    --gray-400: #CED4DA;
    --gray-500: #ADB5BD;
    --gray-600: #6C757D;
    --gray-700: #495057;
    --gray-800: #343A40;
    --gray-900: #212529;
    
    /* 强调色 */
    --accent-yellow: #FFC107;
    --bright-yellow: #FFD700;
    --warning-yellow: #FFA000;
    
    /* 功能色 */
    --success-green: #28A745;
    --error-red: #DC3545;
    --info-cyan: #17A2B8;
    
    /* 间距系统 */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;
    --spacing-xxxl: 4rem;
    
    /* 字体 */
    --font-family: -apple-system, 'Segoe UI', 'Microsoft YaHei', sans-serif;
    
    /* 阴影 */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
    
    /* 圆角 */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-full: 50%;
}

/* ==========================================================================
   2. Reset & Base
   ========================================================================== */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: 16px;
    line-height: 1.6;
    color: var(--gray-700);
    background: #FFFFFF;
}

a {
    color: inherit;
    text-decoration: none;
}

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

ul, ol {
    list-style: none;
}

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

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

/* ==========================================================================
   3. 工具类
   ========================================================================== */
/* 图标尺寸 */
.icon-xs { width: 14px; height: 14px; }
.icon-sm { width: 16px; height: 16px; }
.icon-md { width: 18px; height: 18px; }
.icon-lg { width: 20px; height: 20px; }
.icon-xl { width: 22px; height: 22px; }
.icon-2xl { width: 24px; height: 24px; }
.icon-3xl { width: 28px; height: 28px; }
.icon-4xl { width: 32px; height: 32px; }

/* 间距 */
.mb-xs { margin-bottom: var(--spacing-xs); }
.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }

.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }

/* 文本 */
.text-center { text-align: center; }
.text-primary { color: var(--primary-blue); }
.text-success { color: var(--success-green); }
.text-danger { color: var(--error-red); }
.text-info { color: var(--info-cyan); }

/* ==========================================================================
   4. 主导航 Header
   ========================================================================== */
.main-header {
    background: white;
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-wrapper {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 72px;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-right: auto;
}

.logo-img {
    width: 200px;
}

/* 主导航菜单 */
.main-nav {
    display: flex;
    gap: var(--spacing-lg);
    margin-right: var(--spacing-xl);
}

.main-nav > li {
    position: relative;
}

.main-nav > li > a {
    color: var(--gray-700);
    font-weight: 500;
    padding: var(--spacing-sm) 0;
    position: relative;
    transition: color 0.2s;
    display: flex;
    align-items: center;
    gap: 6px;
}

.main-nav > li > a > i:first-child {
    color: var(--gray-500);
    transition: color 0.2s;
}

.main-nav > li > a:hover,
.main-nav > li > a:hover > i:first-child {
    color: var(--primary-blue);
}

.main-nav > li > a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 3px;
    background: var(--primary-blue);
    transition: width 0.3s;
}

.main-nav > li > a:hover::after {
    width: 100%;
}

.nav-chevron {
    width: 14px;
    height: 14px;
    transition: transform 0.2s;
}

.main-nav > li:hover .nav-chevron {
    transform: rotate(180deg);
}

/* 下拉菜单 */
.nav-dropdown {
    position: absolute;
    top: calc(100% + 12px);
    left: 50%;
    transform: translateX(-50%) translateY(8px);
    min-width: 280px;
    background: white;
    border: 1px solid var(--gray-300);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-md);
    opacity: 0;
    visibility: hidden;
    transition: all 0.2s ease;
    padding: 8px 0;
    z-index: 1001;
}

.main-nav > li:hover .nav-dropdown {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

.nav-dropdown-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    transition: background 0.2s;
}

.nav-dropdown-item:hover {
    background: var(--gray-100);
}

.nav-dropdown-icon {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--light-blue);
    border-radius: 6px;
    color: var(--primary-blue);
    flex-shrink: 0;
}

.nav-dropdown-icon.green {
    background: #E8F5E9;
    color: var(--success-green);
}

.nav-dropdown-icon.red {
    background: #FFEBEE;
    color: var(--error-red);
}

.nav-dropdown-icon.cyan {
    background: #E0F7FA;
    color: var(--info-cyan);
}

.nav-dropdown-title {
    font-size: 14px;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 2px;
}

.nav-dropdown-desc {
    font-size: 12px;
    color: var(--gray-600);
}

/* 导航工具栏 */
.nav-tools {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.nav-contact {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--gray-700);
    font-size: 14px;
    transition: color 0.2s;
}

.nav-contact:hover {
    color: var(--primary-blue);
}

.nav-cta {
    padding: 10px 24px;
    background: var(--accent-yellow);
    color: var(--gray-900);
    border: none;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 14px;
    transition: all 0.2s;
}

.nav-cta:hover {
    background: var(--warning-yellow);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(255, 193, 7, 0.3);
}

/* 移动端菜单按钮 */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    padding: 8px;
}

.mobile-menu-toggle span {
    width: 25px;
    height: 3px;
    background: var(--gray-700);
    border-radius: 2px;
    transition: all 0.3s;
}

/* ==========================================================================
   5. 页脚 Footer
   ========================================================================== */
.footer {
    background: var(--gray-900);
    color: var(--gray-300);
    padding: var(--spacing-xxl) 0;
}

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

.footer-brand h3 {
    font-size: 20px;
    color: white;
    margin-bottom: var(--spacing-xs);
}

.footer-brand .company-en {
    font-size: 12px;
    color: var(--gray-500);
    margin-bottom: var(--spacing-md);
    font-weight: 600;
}

.footer-brand p {
    line-height: 1.7;
    font-size: 14px;
    color: var(--gray-400);
}

.footer-social {
    display: flex;
    gap: var(--spacing-md);
    padding-top: var(--spacing-lg);
}

.social-link {
    width: 40px;
    height: 40px;
    background: var(--gray-800);
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--gray-400);
    transition: all 0.3s;
}

.social-link:hover {
    background: var(--primary-blue);
    color: white;
}

.social-link.wechat:hover {
    background: var(--success-green);
}

.social-link.weibo:hover {
    background: var(--error-red);
}

.footer-links h4 {
    color: white;
    font-size: 16px;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
}

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

.footer-links a {
    color: var(--gray-400);
    font-size: 14px;
    transition: color 0.2s;
}

.footer-links a:hover {
    color: white;
}

.footer-contact-item {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: var(--spacing-sm);
    font-size: 14px;
    color: var(--gray-400);
}

.footer-contact-item i {
    color: var(--primary-blue);
    width: 16px;
}

.footer-bottom {
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--gray-800);
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 14px;
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.footer-legal {
    display: flex;
    gap: var(--spacing-lg);
}

.footer-legal a {
    color: var(--gray-400);
    transition: color 0.2s;
}

.footer-legal a:hover {
    color: white;
}

.footer-disclaimer {
    margin-top: var(--spacing-lg);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--gray-800);
    font-size: 12px;
    color: var(--gray-500);
    text-align: center;
}

/* ==========================================================================
   6. 通用组件
   ========================================================================== */
/* 返回顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--primary-blue);
    color: white;
    border: none;
    border-radius: var(--radius-full);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    transition: all 0.3s;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    background: var(--deep-blue);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
}

/* 通用按钮 */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 32px;
    font-size: 14px;
    font-weight: 600;
    border-radius: var(--radius-sm);
    transition: all 0.2s ease;
    border: none;
    cursor: pointer;
}

.btn-primary {
    background: var(--accent-yellow);
    color: var(--gray-900);
}

.btn-primary:hover {
    background: var(--warning-yellow);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(255, 193, 7, 0.35);
}

.btn-secondary {
    background: transparent;
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.5);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: white;
}

/* 滚动动画 */
.reveal {
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.6s ease-out;
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ==========================================================================
   7. 响应式（全局）
   ========================================================================== */
@media (max-width: 1200px) {
    .footer-grid {
        grid-template-columns: 1fr 1fr;
        gap: var(--spacing-xl);
    }
}

@media (max-width: 968px) {
    .main-nav {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .nav-contact {
        display: none;
    }
}

@media (max-width: 768px) {
    .footer-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }
    
    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-md);
    }
}