/* =========================================
   1. 全局变量与基础重置
   ========================================= */
:root {
    --color-dark: #1a1a1a;
    --color-text-main: #333333;
    --color-text-light: #b0b0b0;
    --color-text-desc: #555555;
    --color-white: #ffffff;
    --font-main: 'Helvetica Neue', Helvetica, Arial, sans-serif;
}

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

body, html {
    width: 100%;
    font-family: var(--font-main);
    background-color: var(--color-white);
    color: var(--color-text-main);
    scroll-behavior: smooth;
}

.container {
    width: 100%;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 40px;
}

/* =========================================
   2. 全局页头
   ========================================= */

.site-header {
    position: absolute; 
    top: 0; left: 0; width: 100%;
    padding: 30px 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 1000; 
    transition: all 0.3s ease;
}

/* 透明背景导航（悬浮在视频/图片上，固定置顶） */
.nav-transparent { 
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    color: var(--color-white);
    text-shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
    background-color: transparent;
    transition: background-color 0.3s ease, color 0.3s ease;
}
.nav-transparent .contact-btn {
    color: var(--color-white);
    border-color: rgba(255, 255, 255, 0.6);
    background-color: rgba(0, 0, 0, 0.3); 
}
.nav-transparent .contact-btn:hover { 
    background-color: var(--color-white); 
    color: #000; 
}

/* 白底导航（用于内页） */
.nav-solid {
    position: fixed;
    top: 0; 
    left: 0;
    width: 100%;
    background-color: var(--color-white);
    color: var(--color-dark);
    box-shadow: 0 1px 5px rgba(0,0,0,0.05);
}
.nav-solid .contact-btn { 
    color: var(--color-dark); 
    border-color: var(--color-dark); 
}
.nav-solid .contact-btn:hover { 
    background-color: var(--color-dark); 
    color: var(--color-white); 
}

.logo {
    font-size: 16px; font-weight: 300;
    letter-spacing: 1px; text-transform: uppercase;
    text-decoration: none; color: inherit;
}

.contact-btn {
    text-decoration: none; font-size: 12px;
    letter-spacing: 1px; text-transform: uppercase;
    border: 1px solid; padding: 8px 16px;
    backdrop-filter: blur(2px); transition: all 0.3s ease;
}

/* =========================================
   3. 全局通用模块：视频首屏 (Hero)
   ★ 从 index.css 移到这里，全站通用
   ========================================= */
.hero-section {
    position: relative; 
    width: 100%; 
    height: 100vh; 
    overflow: hidden; 
    display: flex;
    justify-content: center; 
    align-items: center;
    background-color: #000;
}

.video-container {
    position: absolute; 
    top: 0; left: 0;
    width: 100%; height: 100%; 
    z-index: 1; 
}

.video-container video { 
    width: 100%; 
    height: 100%; 
    object-fit: cover; 
    display: block;
}

.hero-content {
    position: relative; 
    z-index: 2; 
    text-align: center; 
    color: var(--color-white);
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.5); 
    max-width: 900px; 
    padding: 0 20px;
}

.hero-title { font-size: 42px; font-weight: 500; margin-bottom: 30px; line-height: 1.2; }
.hero-desc { font-size: 14px; line-height: 1.6; font-weight: 300; opacity: 0.9; letter-spacing: 0.5px; }

/* =========================================
   4. 全局页脚
   ========================================= */
.site-footer {
    background-color: var(--color-dark);
    color: var(--color-white);
    padding: 80px 0;
    display: flex; justify-content: center;
}

.footer-container {
    display: grid; grid-template-columns: 1fr 1fr; 
    gap: 50px; width: 100%;
}

.footer-title { font-size: 20px; font-weight: 400; margin-bottom: 25px; color: var(--color-white); }
.footer-links { list-style: none; }
.footer-links li { margin-bottom: 12px; }
.footer-links a {
    color: var(--color-text-light); text-decoration: underline; 
    text-underline-offset: 4px; font-size: 14px; transition: color 0.3s ease;
}
.footer-links a:hover { color: var(--color-white); }
.contact-info p { color: var(--color-text-light); font-size: 14px; line-height: 2; margin-bottom: 8px; }

.social-icons {
    margin-top: 20px;
    display: flex;
    gap: 15px;
    align-items: center;
}
.social-icons a {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    text-decoration: none;
}
.social-icons a svg {
    width: 20px;
    height: 20px;
    fill: var(--color-white);
    transition: fill 0.3s ease;
}
.social-icons a:hover svg { fill: var(--color-text-light); }

/* =========================================
   5. 公用响应式适配
   ========================================= */
@media (max-width: 768px) {
    .site-header { padding: 20px; }
    .logo { font-size: 12px; }
    .contact-btn { padding: 6px 12px; font-size: 10px; }
    
    .hero-title { font-size: 26px; margin-bottom: 20px; }
    .hero-desc { font-size: 12px; }

    .site-footer { padding: 50px 0; }
    .footer-container { grid-template-columns: 1fr; gap: 40px; }
    .footer-title { font-size: 18px; margin-bottom: 15px; }
    .contact-info p { font-size: 13px; }
    .container { padding: 0 20px; }
}