/* 全新设计风格：赛博朋克/电竞风 */
:root {
    --primary-color: #00F5D4; /* 霓虹青 */
    --secondary-color: #00BBF9; /* 电竞蓝 */
    --accent-color: #F15BB5; /* 赛博粉 */
    --bg-dark: #0D1B2A; /* 深海蓝 */
    --bg-darker: #070F17; /* 极暗蓝 */
    --bg-card: #1B263B; /* 卡片背景 */
    --text-main: #E0E1DD; /* 主文本 */
    --text-muted: #778DA9; /* 次文本 */
    --border-color: #415A77; /* 边框色 */
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: 'PingFang SC', 'Microsoft YaHei', sans-serif; background-color: var(--bg-darker); color: var(--text-main); line-height: 1.6; }
a { text-decoration: none; color: inherit; transition: all 0.3s ease; }
ul { list-style: none; }
img { max-width: 100%; height: auto; display: block; }

.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }
.section { padding: 80px 0; }
.text-center { text-align: center; }
.mb-4 { margin-bottom: 1.5rem; }
.mb-5 { margin-bottom: 3rem; }
.mt-4 { margin-top: 1.5rem; }

/* Header & Nav */
.header { position: fixed; top: 0; left: 0; width: 100%; background: rgba(13, 27, 42, 0.95); backdrop-filter: blur(10px); z-index: 1000; border-bottom: 1px solid rgba(0, 245, 212, 0.2); }
.header-inner { display: flex; justify-content: space-between; align-items: center; height: 70px; }
.logo { display: flex; align-items: center; gap: 10px; font-size: 24px; font-weight: bold; color: var(--primary-color); }
.nav-menu { display: flex; gap: 25px; }
.nav-menu a { font-size: 16px; font-weight: 500; position: relative; }
.nav-menu a:hover, .nav-menu a.active { color: var(--primary-color); }
.nav-menu a::after { content: ''; position: absolute; bottom: -5px; left: 0; width: 0; height: 2px; background: var(--primary-color); transition: width 0.3s; }
.nav-menu a:hover::after, .nav-menu a.active::after { width: 100%; }

/* Search Box */
.search-box { display: flex; align-items: center; background: var(--bg-card); border-radius: 20px; padding: 5px 15px; border: 1px solid var(--border-color); }
.search-input { background: transparent; border: none; color: var(--text-main); outline: none; width: 200px; }
.search-btn { background: transparent; border: none; cursor: pointer; color: var(--text-muted); }

/* Mobile Menu */
.mobile-menu-btn { display: none; background: transparent; border: none; cursor: pointer; flex-direction: column; gap: 5px; }
.mobile-menu-btn span { width: 25px; height: 3px; background: var(--primary-color); transition: 0.3s; }

/* Hero Section */
.hero { height: 100vh; min-height: 600px; position: relative; display: flex; align-items: center; background-size: cover; background-position: center; }
.hero-overlay { position: absolute; top: 0; left: 0; width: 100%; height: 100%; background: linear-gradient(90deg, rgba(7,15,23,0.9) 0%, rgba(7,15,23,0.6) 50%, rgba(7,15,23,0.2) 100%); }
.hero-content { position: relative; z-index: 1; max-width: 600px; }
.hero-title { font-size: 48px; line-height: 1.2; margin-bottom: 20px; text-transform: uppercase; }
.hero-title span { color: var(--primary-color); text-shadow: 0 0 10px rgba(0,245,212,0.5); }
.hero-desc { font-size: 18px; color: var(--text-muted); margin-bottom: 30px; }

/* Buttons */
.btn { display: inline-block; padding: 12px 30px; border-radius: 30px; font-weight: bold; text-transform: uppercase; letter-spacing: 1px; cursor: pointer; border: none; }
.btn-primary { background: linear-gradient(45deg, var(--primary-color), var(--secondary-color)); color: var(--bg-darker); box-shadow: 0 0 15px rgba(0,245,212,0.4); }
.btn-primary:hover { box-shadow: 0 0 25px rgba(0,245,212,0.6); transform: translateY(-2px); }
.btn-outline { background: transparent; border: 2px solid var(--primary-color); color: var(--primary-color); }
.btn-outline:hover { background: rgba(0,245,212,0.1); }

/* Grids */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 30px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 30px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }

/* Cards */
.card { background: var(--bg-card); border-radius: 12px; overflow: hidden; border: 1px solid var(--border-color); transition: transform 0.3s, box-shadow 0.3s; }
.card:hover { transform: translateY(-5px); box-shadow: 0 10px 20px rgba(0,0,0,0.5); border-color: var(--primary-color); }
.card-img { position: relative; overflow: hidden; aspect-ratio: 16/9; }
.card-img img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.5s; }
.card:hover .card-img img { transform: scale(1.05); }
.card-body { padding: 20px; }

/* Video Specific */
.play-btn { position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); width: 50px; height: 50px; background: rgba(0,245,212,0.8); border-radius: 50%; display: flex; justify-content: center; align-items: center; color: var(--bg-darker); font-size: 20px; opacity: 0; transition: 0.3s; }
.card:hover .play-btn { opacity: 1; }
.duration { position: absolute; bottom: 10px; right: 10px; background: rgba(0,0,0,0.8); padding: 2px 8px; border-radius: 4px; font-size: 12px; }
.tag { display: inline-block; padding: 4px 10px; background: rgba(0,187,249,0.2); color: var(--secondary-color); border-radius: 4px; font-size: 12px; margin-bottom: 10px; }

/* Experts */
.expert-card { text-align: center; padding: 30px 20px; }
.expert-img { width: 120px; height: 120px; border-radius: 50%; margin: 0 auto 20px; border: 3px solid var(--primary-color); padding: 3px; }
.expert-img img { width: 100%; height: 100%; border-radius: 50%; object-fit: cover; }

/* FAQ */
.faq-item { background: var(--bg-card); border: 1px solid var(--border-color); border-radius: 8px; margin-bottom: 15px; overflow: hidden; }
.faq-q { padding: 20px; cursor: pointer; display: flex; justify-content: space-between; align-items: center; font-weight: bold; }
.faq-a { padding: 0 20px; max-height: 0; overflow: hidden; transition: max-height 0.3s ease, padding 0.3s ease; color: var(--text-muted); }
.faq-item.active .faq-a { padding: 0 20px 20px; max-height: 200px; }
.faq-item.active .faq-q { color: var(--primary-color); }

/* Footer */
.footer { background: var(--bg-dark); padding: 60px 0 20px; border-top: 1px solid var(--border-color); }
.footer-grid { display: grid; grid-template-columns: 2fr 1.5fr 1fr 1.5fr; gap: 40px; margin-bottom: 40px; }
.footer-logo { display: flex; align-items: center; gap: 10px; font-size: 24px; font-weight: bold; color: var(--primary-color); margin-bottom: 20px; }
.social-links { display: flex; gap: 15px; margin-top: 20px; }
.share-icon { width: 40px; height: 40px; border-radius: 50%; background: var(--bg-card); display: flex; justify-content: center; align-items: center; font-size: 20px; }
.share-icon:hover { background: var(--primary-color); color: var(--bg-darker); }
.contact-list li { margin-bottom: 10px; color: var(--text-muted); }
.footer-links li { margin-bottom: 10px; }
.footer-links a:hover { color: var(--primary-color); padding-left: 5px; }
.qrcode-box { display: flex; gap: 20px; }
.qr-item { text-align: center; font-size: 12px; color: var(--text-muted); }
.qr-item img { border-radius: 8px; margin-bottom: 5px; }
.footer-bottom { text-align: center; padding-top: 20px; border-top: 1px solid var(--border-color); color: var(--text-muted); font-size: 14px; }

/* Back to Top */
.back-to-top { position: fixed; bottom: 30px; right: 30px; width: 40px; height: 40px; background: var(--primary-color); color: var(--bg-darker); border: none; border-radius: 50%; font-size: 20px; cursor: pointer; opacity: 0; visibility: hidden; transition: 0.3s; z-index: 99; }
.back-to-top.visible { opacity: 1; visibility: visible; }

/* Responsive */
@media (max-width: 992px) {
    .grid-4 { grid-template-columns: repeat(2, 1fr); }
    .footer-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
    .grid-2, .grid-3 { grid-template-columns: 1fr; }
    .nav-menu { position: fixed; top: 70px; left: -100%; width: 100%; height: calc(100vh - 70px); background: var(--bg-dark); flex-direction: column; align-items: center; justify-content: center; transition: 0.3s; }
    .nav-menu.active { left: 0; }
    .mobile-menu-btn { display: flex; }
    .search-box { display: none; }
    .hero-title { font-size: 36px; }
}