/* ============================================
   新幕影视官网 - 主样式表
   深蓝科技风格
   ============================================ */

/* CSS变量 */
:root {
    --bg-deep: #040810;
    --bg-dark: #0a1628;
    --bg-card: rgba(0, 180, 255, 0.05);
    --bg-card-solid: #0d1a2e;
    --primary: #00b4ff;
    --primary-light: #38d9ff;
    --primary-dim: #0284c7;
    --red: #b8312f;
    --red-light: #e05050;
    --text: #f0f4f8;
    --text-dim: #a8b8c8;
    --text-faint: #5a6a7a;
    --border: rgba(0, 180, 255, 0.2);
    --border-solid: #1a2a40;
    --gradient-primary: linear-gradient(135deg, #00b4ff 0%, #38d9ff 100%);
    --gradient-bg: linear-gradient(135deg, #040810 0%, #0a1628 40%, #081a1c 70%, #040810 100%);
    --shadow-card: 0 10px 40px rgba(0, 0, 0, 0.4);
    --shadow-glow: 0 0 30px rgba(0, 180, 255, 0.2);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --container-max: 1200px;
}

/* 重置 */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
    background: var(--bg-deep);
    color: var(--text);
    line-height: 1.8;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}
a { text-decoration: none; color: inherit; transition: var(--transition); }
ul, ol { list-style: none; }
img { max-width: 100%; height: auto; display: block; }
button { cursor: pointer; border: none; background: none; font-family: inherit; }
input, textarea, select { font-family: inherit; font-size: inherit; outline: none; }

/* 容器 */
.container { max-width: var(--container-max); margin: 0 auto; padding: 0 24px; }
.main-content { min-height: calc(100vh - 80px); }

/* 通用按钮 */
.btn {
    display: inline-flex; align-items: center; justify-content: center;
    padding: 12px 32px; font-size: 15px; font-weight: 500;
    border-radius: 4px; transition: var(--transition); cursor: pointer; letter-spacing: 1px;
    border: none;
}
.btn-primary {
    background: var(--gradient-primary); color: var(--bg-deep);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: var(--shadow-glow); }
.btn-outline {
    background: transparent; color: var(--primary); border: 1px solid var(--primary);
}
.btn-outline:hover { background: var(--primary); color: var(--bg-deep); transform: translateY(-2px); }
.btn-red { background: var(--red); color: #fff; }
.btn-red:hover { background: var(--red-light); transform: translateY(-2px); }

/* 通用板块标题 */
.section { padding: 80px 0; position: relative; }
.section-header { text-align: center; margin-bottom: 50px; }
.section-label {
    display: inline-block; font-size: 12px; letter-spacing: 6px;
    color: var(--primary-dim); text-transform: uppercase; margin-bottom: 10px;
}
.section-title {
    font-size: 36px; font-weight: 700; color: var(--text);
    margin-bottom: 14px; letter-spacing: 3px;
}
.section-line {
    width: 50px; height: 2px; background: var(--gradient-primary);
    margin: 0 auto 16px; border-radius: 2px;
}
.section-desc { font-size: 15px; color: var(--text-dim); max-width: 650px; margin: 0 auto; }

/* ========== 导航栏 ========== */
.header {
    position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
    transition: var(--transition); background: rgba(4, 8, 16, 0.85);
    backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid transparent;
}
.header.scrolled {
    background: rgba(4, 8, 16, 0.95);
    border-bottom-color: var(--border);
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
}
.navbar { display: flex; align-items: center; justify-content: space-between; height: 70px; }
.logo { display: flex; align-items: center; gap: 10px; }
.logo-img { height: 36px; width: auto; border-radius: 4px; }
.logo-text {
    font-size: 20px; font-weight: 700; letter-spacing: 3px;
    background: var(--gradient-primary); -webkit-background-clip: text;
    -webkit-text-fill-color: transparent; background-clip: text;
}
.nav-menu { display: flex; align-items: center; gap: 32px; }
.nav-link {
    font-size: 14px; color: var(--text-dim); position: relative;
    padding: 6px 0; font-weight: 400; letter-spacing: 1px;
}
.nav-link::after {
    content: ''; position: absolute; bottom: 0; left: 0; width: 0;
    height: 2px; background: var(--gradient-primary); transition: var(--transition);
}
.nav-link:hover, .nav-link.active { color: var(--primary-light); }
.nav-link:hover::after, .nav-link.active::after { width: 100%; }
.hamburger {
    display: none; flex-direction: column; gap: 5px;
    cursor: pointer; padding: 8px;
}
.hamburger span {
    width: 22px; height: 2px; background: var(--text);
    transition: var(--transition); border-radius: 2px;
}
.hamburger.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.hamburger.active span:nth-child(2) { opacity: 0; }
.hamburger.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* ========== Hero ========== */
.hero {
    position: relative; min-height: 100vh; display: flex;
    align-items: center; overflow: hidden; padding-top: 70px;
}
.hero-bg {
    position: absolute; top: 0; left: 0; right: 0; bottom: 0;
    background:
        radial-gradient(ellipse at 25% 15%, rgba(0, 180, 255, 0.2) 0%, transparent 45%),
        radial-gradient(ellipse at 75% 85%, rgba(0, 255, 136, 0.1) 0%, transparent 45%),
        radial-gradient(ellipse at 50% 50%, rgba(0, 180, 255, 0.06) 0%, transparent 60%),
        var(--gradient-bg);
    z-index: 1;
}
.hero-bg::before {
    content: ''; position: absolute; top: 0; left: 0; right: 0; bottom: 0;
    background: repeating-linear-gradient(0deg, transparent, transparent 2px, rgba(255,255,255,0.01) 2px, rgba(255,255,255,0.01) 4px);
}
.hero-light {
    position: absolute; width: 500px; height: 500px; border-radius: 50%;
    background: radial-gradient(circle, rgba(0, 180, 255, 0.12) 0%, transparent 70%);
    top: 50%; left: 50%; transform: translate(-50%, -50%);
    animation: pulse 6s ease-in-out infinite; z-index: 1;
}
@keyframes pulse {
    0%, 100% { opacity: 0.5; transform: translate(-50%,-50%) scale(1); }
    50% { opacity: 1; transform: translate(-50%,-50%) scale(1.1); }
}
.hero .container { position: relative; z-index: 2; }
.hero-content { max-width: 750px; animation: fadeInUp 1s ease-out; }
.hero-brand {
    font-size: 13px; color: var(--primary-dim); letter-spacing: 8px;
    margin-bottom: 20px; text-transform: uppercase;
}
.hero-title {
    font-size: 52px; font-weight: 900; line-height: 1.3;
    margin-bottom: 16px; letter-spacing: 4px;
    text-shadow: 0 0 40px rgba(0, 180, 255, 0.3);
}
.hero-title span { color: var(--primary); }
.hero-slogan {
    font-size: 28px; color: var(--primary-light); letter-spacing: 12px;
    margin-bottom: 24px; font-weight: 300;
}
.hero-divider {
    width: 150px; height: 1px;
    background: linear-gradient(90deg, transparent, var(--primary), transparent);
    margin-bottom: 24px;
}
.hero-desc {
    font-size: 15px; color: var(--text-dim); line-height: 2;
    margin-bottom: 36px; max-width: 600px; letter-spacing: 1px;
}
.hero-desc strong { color: var(--primary); font-weight: 500; }
.hero-buttons { display: flex; gap: 16px; flex-wrap: wrap; }
.hero-scroll {
    position: absolute; bottom: 30px; left: 50%; transform: translateX(-50%);
    color: var(--text-faint); font-size: 11px; letter-spacing: 3px;
    animation: bounce 2s infinite; z-index: 2;
}
@keyframes bounce {
    0%, 100% { transform: translateX(-50%) translateY(0); }
    50% { transform: translateX(-50%) translateY(-8px); }
}
@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(30px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ========== 核心数据 ========== */
.stats { padding: 50px 0; background: var(--bg-dark); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 30px; text-align: center; }
.stat-item .stat-num {
    font-size: 42px; font-weight: 700; color: var(--primary);
    line-height: 1; margin-bottom: 8px;
}
.stat-item .stat-label { font-size: 14px; color: var(--text-dim); letter-spacing: 2px; }

/* ========== 卡片通用 ========== */
.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 24px; }
.card {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: 10px; padding: 30px; transition: var(--transition);
    position: relative; overflow: hidden;
}
.card:hover {
    border-color: rgba(0, 180, 255, 0.5); transform: translateY(-6px);
    box-shadow: var(--shadow-card); background: rgba(0, 180, 255, 0.08);
}
.card-icon { font-size: 36px; margin-bottom: 16px; display: block; }
.card h3 { font-size: 19px; color: var(--primary-light); margin-bottom: 12px; font-weight: 600; }
.card p { font-size: 14px; color: var(--text-dim); line-height: 1.9; }

/* ========== 作品/新闻列表 ========== */
.list-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 24px; }
.list-item {
    background: var(--bg-card-solid); border: 1px solid var(--border-solid);
    border-radius: 10px; overflow: hidden; transition: var(--transition);
    display: flex; flex-direction: column;
}
.list-item:hover {
    transform: translateY(-6px); box-shadow: var(--shadow-card);
    border-color: var(--primary-dim);
}
.list-cover {
    aspect-ratio: 16/10; background: var(--bg-dark);
    display: flex; align-items: center; justify-content: center;
    overflow: hidden; position: relative;
}
.list-cover img { width: 100%; height: 100%; object-fit: cover; }
.list-cover-placeholder {
    color: var(--text-faint); font-size: 14px; letter-spacing: 2px;
    background: linear-gradient(135deg, rgba(0,180,255,0.1), rgba(0,0,0,0.3));
    width: 100%; height: 100%; display: flex; align-items: center; justify-content: center;
}
.list-badge {
    position: absolute; top: 12px; left: 12px;
    padding: 4px 12px; background: var(--red); color: #fff;
    font-size: 11px; border-radius: 3px; letter-spacing: 1px; z-index: 2;
}
.list-category {
    position: absolute; top: 12px; right: 12px;
    padding: 4px 12px; background: rgba(0, 180, 255, 0.8); color: var(--bg-deep);
    font-size: 11px; border-radius: 3px; letter-spacing: 1px; z-index: 2;
}
.list-body { padding: 20px; flex-grow: 1; display: flex; flex-direction: column; }
.list-title {
    font-size: 17px; color: var(--text); margin-bottom: 10px;
    font-weight: 600; line-height: 1.5;
}
.list-item:hover .list-title { color: var(--primary-light); }
.list-summary { font-size: 13px; color: var(--text-dim); line-height: 1.8; flex-grow: 1; margin-bottom: 14px; }
.list-meta {
    display: flex; justify-content: space-between; align-items: center;
    padding-top: 12px; border-top: 1px solid var(--border-solid);
    font-size: 12px; color: var(--text-faint);
}
.list-more { color: var(--primary); }
.list-more:hover { color: var(--primary-light); }

/* 筛选标签 */
.filter-tabs { display: flex; gap: 10px; margin-bottom: 36px; flex-wrap: wrap; justify-content: center; }
.filter-tab {
    padding: 8px 22px; border: 1px solid var(--border); border-radius: 20px;
    font-size: 13px; color: var(--text-dim); cursor: pointer; transition: var(--transition);
    background: transparent;
}
.filter-tab:hover, .filter-tab.active {
    background: var(--primary); color: var(--bg-deep); border-color: var(--primary);
}

/* 分页 */
.pagination { display: flex; justify-content: center; gap: 8px; margin-top: 40px; }
.pagination a, .pagination span {
    padding: 8px 16px; border: 1px solid var(--border-solid); border-radius: 4px;
    font-size: 14px; color: var(--text-dim); transition: var(--transition);
}
.pagination a:hover { border-color: var(--primary); color: var(--primary); }
.pagination .current { background: var(--primary); color: var(--bg-deep); border-color: var(--primary); }

/* ========== 详情页 ========== */
.detail-hero { padding: 120px 0 50px; background: var(--bg-dark); border-bottom: 1px solid var(--border); }
.detail-category { display: inline-block; padding: 5px 16px; background: rgba(0,180,255,0.1); border: 1px solid var(--primary-dim); border-radius: 4px; font-size: 12px; color: var(--primary-light); margin-bottom: 16px; letter-spacing: 1px; }
.detail-title { font-size: 32px; font-weight: 700; color: var(--text); margin-bottom: 16px; line-height: 1.4; }
.detail-meta { display: flex; gap: 24px; font-size: 13px; color: var(--text-faint); flex-wrap: wrap; }
.detail-content { padding: 50px 0; }
.detail-content .content-body { max-width: 800px; margin: 0 auto; }
.detail-content .content-body p { font-size: 15px; color: var(--text-dim); line-height: 2; margin-bottom: 20px; }
.detail-content .content-cover { max-width: 800px; margin: 0 auto 40px; border-radius: 10px; overflow: hidden; }
.detail-content .content-cover img { width: 100%; }

/* ========== 黄河西岸专题页 ========== */
.huanghe-hero {
    position: relative; min-height: 80vh; display: flex; align-items: center;
    padding-top: 70px; overflow: hidden;
}
.huanghe-hero .hero-bg {
    background:
        radial-gradient(ellipse at 30% 40%, rgba(184, 49, 47, 0.2) 0%, transparent 50%),
        radial-gradient(ellipse at 70% 60%, rgba(0, 180, 255, 0.15) 0%, transparent 50%),
        linear-gradient(135deg, #0a0810 0%, #1a0e0e 50%, #0a1628 100%);
}
.huanghe-badge {
    display: inline-block; padding: 6px 20px; background: var(--red);
    color: #fff; font-size: 13px; border-radius: 4px; letter-spacing: 2px;
    margin-bottom: 24px;
}
.huanghe-title {
    font-size: 64px; font-weight: 900; letter-spacing: 12px;
    margin-bottom: 16px; background: linear-gradient(135deg, #fff 0%, var(--primary-light) 100%);
    -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
}
.huanghe-subtitle { font-size: 18px; color: var(--text-dim); letter-spacing: 6px; margin-bottom: 30px; }
.huanghe-section { padding: 70px 0; }
.huanghe-section:nth-child(even) { background: var(--bg-dark); }
.huanghe-highlight {
    background: linear-gradient(135deg, rgba(184,49,47,0.1), rgba(0,180,255,0.06));
    border: 1px solid var(--border); border-left: 3px solid var(--red);
    padding: 28px 32px; border-radius: 0 10px 10px 0; margin: 24px 0;
}
.huanghe-highlight h4 { color: var(--red-light); font-size: 15px; margin-bottom: 8px; letter-spacing: 2px; }
.huanghe-highlight p { color: var(--text); font-size: 15px; line-height: 1.9; }
.huanghe-tags { display: flex; gap: 10px; flex-wrap: wrap; margin: 20px 0; }
.huanghe-tag {
    padding: 6px 18px; background: rgba(0,180,255,0.1);
    border: 1px solid var(--primary-dim); border-radius: 20px;
    font-size: 13px; color: var(--primary-light);
}
.huanghe-tag.red { background: rgba(184,49,47,0.1); border-color: rgba(184,49,47,0.3); color: var(--red-light); }
.huanghe-formats { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; margin-top: 30px; }
.format-card {
    background: var(--bg-card); border: 1px solid var(--border); border-radius: 8px;
    padding: 24px; text-align: center; transition: var(--transition);
}
.format-card:hover { border-color: var(--primary); transform: translateY(-4px); }
.format-card .format-icon { font-size: 32px; margin-bottom: 10px; }
.format-card h5 { font-size: 15px; color: var(--primary-light); margin-bottom: 6px; }
.format-card p { font-size: 12px; color: var(--text-faint); }

/* ========== 关于我们 ========== */
.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 50px; align-items: center; }
.about-text h3 { font-size: 24px; color: var(--primary-light); margin-bottom: 20px; letter-spacing: 2px; }
.about-text p { font-size: 15px; color: var(--text-dim); line-height: 2; margin-bottom: 16px; }
.culture-list { display: grid; gap: 14px; margin-top: 24px; }
.culture-item {
    display: flex; gap: 16px; padding: 16px 20px;
    background: var(--bg-card); border-radius: 8px; border-left: 3px solid var(--primary);
}
.culture-label { flex-shrink: 0; font-size: 13px; color: var(--primary); font-weight: 600; min-width: 70px; }
.culture-value { font-size: 14px; color: var(--text-dim); line-height: 1.7; }
.about-image {
    aspect-ratio: 4/3; border-radius: 12px; overflow: hidden;
    background: linear-gradient(135deg, rgba(0,180,255,0.15), rgba(0,0,0,0.5));
    display: flex; align-items: center; justify-content: center;
    border: 1px solid var(--border);
}
.about-image span { font-size: 48px; opacity: 0.5; }

/* 资质卡片 */
.qual-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 20px; }
.qual-card {
    background: var(--bg-card); border: 1px solid var(--border); border-radius: 10px;
    padding: 28px; transition: var(--transition); position: relative; overflow: hidden;
}
.qual-card::before {
    content: ''; position: absolute; top: 0; left: 0; width: 40px; height: 40px;
    border-top: 2px solid var(--primary); border-left: 2px solid var(--primary);
    opacity: 0; transition: opacity 0.3s;
}
.qual-card:hover { border-color: rgba(0,180,255,0.5); transform: translateY(-4px); }
.qual-card:hover::before { opacity: 1; }
.qual-icon { font-size: 28px; margin-bottom: 14px; display: block; }
.qual-name { font-size: 17px; color: var(--primary-light); margin-bottom: 10px; font-weight: 600; }
.qual-desc { font-size: 13px; color: var(--text-dim); line-height: 1.8; margin-bottom: 14px; }
.qual-meta { padding-top: 12px; border-top: 1px solid var(--border-solid); font-size: 12px; color: var(--primary-dim); line-height: 1.7; }

/* ========== 联系我们 ========== */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; }
.contact-info h3 { font-size: 24px; color: var(--text); margin-bottom: 16px; }
.contact-info > p { font-size: 15px; color: var(--text-dim); line-height: 2; margin-bottom: 30px; }
.contact-list { display: grid; gap: 18px; }
.contact-item { display: flex; gap: 14px; align-items: flex-start; }
.contact-item .icon { font-size: 22px; flex-shrink: 0; margin-top: 2px; }
.contact-item .label { font-size: 12px; color: var(--text-faint); display: block; }
.contact-item .value { font-size: 15px; color: var(--text); }
.contact-form {
    background: var(--bg-card-solid); padding: 36px; border-radius: 12px;
    border: 1px solid var(--border-solid);
}
.contact-form h3 { font-size: 20px; color: var(--text); margin-bottom: 24px; text-align: center; }
.form-group { margin-bottom: 18px; }
.form-group input, .form-group textarea, .form-group select {
    width: 100%; padding: 12px 16px; background: var(--bg-deep);
    border: 1px solid var(--border-solid); border-radius: 6px; color: var(--text);
    font-size: 14px; transition: var(--transition);
}
.form-group input:focus, .form-group textarea:focus, .form-group select:focus {
    border-color: var(--primary); box-shadow: 0 0 0 3px rgba(0,180,255,0.1);
}
.form-group textarea { resize: vertical; min-height: 100px; }
.form-group input::placeholder, .form-group textarea::placeholder { color: var(--text-faint); }
.form-message { padding: 12px 16px; border-radius: 6px; margin-bottom: 16px; font-size: 14px; text-align: center; }
.form-message.success { background: rgba(76,175,80,0.1); color: #81c784; border: 1px solid rgba(76,175,80,0.3); }
.form-message.error { background: rgba(244,67,54,0.1); color: #e57373; border: 1px solid rgba(244,67,54,0.3); }

/* ========== 页脚 ========== */
.footer { background: var(--bg-darker, #030610); padding: 50px 0 0; border-top: 1px solid var(--border); }
.footer-content { display: grid; grid-template-columns: 2fr 1fr 1fr 1.5fr; gap: 36px; padding-bottom: 36px; }
.footer-brand .footer-logo { display: flex; align-items: center; gap: 10px; font-size: 18px; font-weight: 700; margin-bottom: 14px; }
.footer-brand .footer-logo img { height: 30px; border-radius: 4px; }
.footer-slogan { font-size: 16px; color: var(--primary); letter-spacing: 6px; margin-bottom: 10px; }
.footer-desc { font-size: 13px; color: var(--text-dim); line-height: 1.8; }
.footer-links h4, .footer-contact h4 { font-size: 15px; color: var(--text); margin-bottom: 16px; font-weight: 600; }
.footer-links ul { display: grid; gap: 10px; }
.footer-links a { font-size: 13px; color: var(--text-dim); }
.footer-links a:hover { color: var(--primary); }
.footer-contact p { font-size: 13px; color: var(--text-dim); margin-bottom: 10px; line-height: 1.6; }
.footer-contact .contact-icon { margin-right: 6px; }
.footer-bottom {
    padding: 20px 0; border-top: 1px solid var(--border-solid);
    display: flex; justify-content: space-between; align-items: center;
    flex-wrap: wrap; gap: 10px;
}
.footer-bottom p { font-size: 12px; color: var(--text-faint); }

/* 返回顶部 */
.back-to-top {
    position: fixed; bottom: 24px; right: 24px; width: 44px; height: 44px;
    background: var(--gradient-primary); color: var(--bg-deep); border-radius: 50%;
    font-size: 18px; font-weight: 700; display: flex; align-items: center; justify-content: center;
    opacity: 0; visibility: hidden; transition: var(--transition); z-index: 999;
    box-shadow: var(--shadow-glow);
}
.back-to-top.visible { opacity: 1; visibility: visible; }
.back-to-top:hover { transform: translateY(-4px); }

/* 滚动动画 */
.fade-in { opacity: 0; transform: translateY(24px); transition: opacity 0.7s ease, transform 0.7s ease; }
.fade-in.visible { opacity: 1; transform: translateY(0); }

/* ========== 响应式 ========== */
@media (max-width: 1024px) {
    .section { padding: 60px 0; }
    .section-title { font-size: 30px; }
    .hero-title { font-size: 40px; letter-spacing: 3px; }
    .hero-slogan { font-size: 22px; letter-spacing: 8px; }
    .huanghe-title { font-size: 48px; letter-spacing: 8px; }
    .about-grid, .contact-grid { grid-template-columns: 1fr; gap: 36px; }
    .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 24px; }
    .footer-content { grid-template-columns: 1fr 1fr; gap: 28px; }
}

@media (max-width: 768px) {
    .container { padding: 0 18px; }
    .section { padding: 50px 0; }
    .section-header { margin-bottom: 36px; }
    .section-title { font-size: 26px; letter-spacing: 2px; }
    .section-label { font-size: 11px; letter-spacing: 4px; }
    
    /* 移动端导航 */
    .hamburger { display: flex; }
    .nav-menu {
        position: fixed; top: 70px; left: 0; right: 0;
        background: rgba(4, 8, 16, 0.98); backdrop-filter: blur(10px);
        flex-direction: column; padding: 20px; gap: 0;
        transform: translateY(-100%); opacity: 0; visibility: hidden;
        transition: var(--transition); border-bottom: 1px solid var(--border);
    }
    .nav-menu.active { transform: translateY(0); opacity: 1; visibility: visible; }
    .nav-menu li { width: 100%; text-align: center; }
    .nav-link { display: block; padding: 14px 0; font-size: 15px; border-bottom: 1px solid var(--border-solid); }
    .nav-link::after { display: none; }
    
    /* Hero */
    .hero { min-height: 90vh; }
    .hero-title { font-size: 30px; letter-spacing: 2px; }
    .hero-slogan { font-size: 18px; letter-spacing: 6px; }
    .hero-desc { font-size: 14px; }
    .hero-buttons { flex-direction: column; }
    .hero-buttons .btn { width: 100%; }
    
    .huanghe-hero { min-height: 70vh; }
    .huanghe-title { font-size: 36px; letter-spacing: 6px; }
    .huanghe-subtitle { font-size: 14px; letter-spacing: 4px; }
    
    .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 20px; }
    .stat-item .stat-num { font-size: 32px; }
    
    .list-grid { grid-template-columns: 1fr; }
    .card-grid { grid-template-columns: 1fr; }
    
    .detail-title { font-size: 24px; }
    .detail-hero { padding: 100px 0 40px; }
    
    .contact-form { padding: 24px; }
    
    .footer-content { grid-template-columns: 1fr; text-align: center; gap: 28px; }
    .footer-brand .footer-logo { justify-content: center; }
    .footer-bottom { flex-direction: column; text-align: center; }
    
    .back-to-top { bottom: 16px; right: 16px; width: 40px; height: 40px; }
}

@media (max-width: 480px) {
    .hero-title { font-size: 26px; }
    .hero-slogan { font-size: 16px; letter-spacing: 4px; }
    .section-title { font-size: 22px; }
    .huanghe-title { font-size: 28px; letter-spacing: 4px; }
    .btn { padding: 10px 24px; font-size: 14px; }
}