/* sdivc.com 主样式 - 工业余热回收换热器网站 v2 */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --primary: #1a5fa8;
  --primary-dark: #0d3f78;
  --primary-light: #e8f0fe;
  --accent: #e65c00;
  --accent-dark: #c44e00;
  --red: #e74c3c;
  --red-dark: #c0392b;
  --text: #222;
  --text-muted: #666;
  --border: #e0e0e0;
  --bg-light: #f5f7fa;
  --bg-dark: #1a2636;
  --bg-darker: #111827;
  --radius: 8px;
  --radius-sm: 4px;
  --radius-lg: 12px;
  --shadow: 0 2px 12px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 20px rgba(0,0,0,0.1);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.14);
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html { scroll-behavior: smooth; }

body { font-family: 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif; color: var(--text); line-height: 1.7; font-size: 15px; overflow-x: hidden; }

a { color: var(--primary); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--accent); }
img { max-width: 100%; height: auto; display: block; }
ul { list-style: none; }

.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* ===== 顶栏 ===== */
.topbar { background: var(--bg-dark); color: #aaa; font-size: 13px; padding: 6px 0; }
.topbar .container { display: flex; gap: 20px; align-items: center; }
.topbar a { color: #aaa; transition: color 0.2s; }
.topbar a:hover { color: #fff; }
.topbar .lang-switch { margin-left: auto; border: 1px solid #555; padding: 2px 10px; border-radius: 3px; cursor: pointer; transition: all 0.2s; }
.topbar .lang-switch:hover { border-color: #fff; color: #fff; }

/* ===== 导航 ===== */
.site-header { background: #fff; box-shadow: 0 2px 8px rgba(0,0,0,0.06); position: sticky; top: 0; z-index: 100; transition: box-shadow var(--transition); }
.site-header.scrolled { box-shadow: 0 4px 20px rgba(0,0,0,0.1); }
.site-header .container { display: flex; align-items: center; height: 70px; gap: 40px; transition: height var(--transition); }
.site-header.scrolled .container { height: 60px; }
.logo { display: flex; flex-direction: column; }
.logo strong { font-size: 20px; color: var(--primary); font-weight: 700; letter-spacing: 0.5px; }
.logo span { font-size: 12px; color: var(--text-muted); }
.main-nav ul { display: flex; gap: 5px; }
.main-nav a { padding: 8px 14px; display: block; color: var(--text); font-size: 14px; border-radius: var(--radius-sm); transition: all 0.2s; position: relative; }
.main-nav a::after { content: ''; position: absolute; bottom: 4px; left: 14px; right: 14px; height: 2px; background: var(--primary); transform: scaleX(0); transition: transform var(--transition); }
.main-nav a:hover::after,
.main-nav a.active::after { transform: scaleX(1); }
.main-nav a:hover, .main-nav a.active { color: var(--primary); }
.btn-contact { background: var(--red) !important; color: #fff !important; border-radius: var(--radius-sm); }
.btn-contact::after { display: none; }
.btn-contact:hover { background: var(--red-dark) !important; transform: translateY(-1px); }
.has-sub { position: relative; }
.submenu { display: none; position: absolute; top: 100%; left: 0; background: #fff; box-shadow: var(--shadow-md); border: 1px solid var(--border); min-width: 200px; border-radius: var(--radius); z-index: 200; opacity: 0; transform: translateY(8px); transition: all 0.25s; }
.has-sub:hover .submenu { display: block; opacity: 1; transform: translateY(0); }
.submenu li a { padding: 11px 18px; color: var(--text); border-bottom: 1px solid #f0f0f0; }
.submenu li a:hover { background: var(--primary-light); color: var(--primary); }
.mobile-menu-btn { display: none; background: none; border: 1px solid var(--border); padding: 8px 12px; cursor: pointer; font-size: 18px; margin-left: auto; border-radius: var(--radius-sm); }

/* ===== 按钮 ===== */
.btn-primary { display: inline-block; background: var(--primary); color: #fff !important; padding: 11px 28px; border-radius: var(--radius-sm); font-size: 15px; font-weight: 500; transition: all var(--transition); border: none; cursor: pointer; position: relative; overflow: hidden; }
.btn-primary:hover { background: var(--primary-dark); transform: translateY(-2px); box-shadow: 0 6px 20px rgba(26,95,168,0.3); }
.btn-primary:active { transform: translateY(0); }
.btn-outline { display: inline-block; border: 2px solid var(--primary); color: var(--primary) !important; padding: 9px 24px; border-radius: var(--radius-sm); font-size: 15px; transition: all var(--transition); }
.btn-outline:hover { background: var(--primary); color: #fff !important; transform: translateY(-2px); }
.btn-accent { background: var(--accent); }
.btn-accent:hover { background: var(--accent-dark); }
.btn-red { background: var(--red); }
.btn-red:hover { background: var(--red-dark); box-shadow: 0 6px 20px rgba(231,76,60,0.3); }

/* ===== Hero ===== */
.hero { background: linear-gradient(135deg, #1a2636 0%, #1a5fa8 100%); color: #fff; padding: 100px 0 90px; position: relative; overflow: hidden; }
.hero::before { content: ''; position: absolute; inset: 0; background: radial-gradient(circle at 30% 50%, rgba(255,255,255,0.06) 0%, transparent 60%); animation: heroGlow 4s ease-in-out infinite alternate; }
@keyframes heroGlow { from { opacity: 0.5; } to { opacity: 1; } }
.hero h1 { font-size: 48px; font-weight: 700; margin-bottom: 16px; line-height: 1.2; animation: fadeInUp 0.6s ease-out; }
.hero p { font-size: 18px; opacity: .85; margin-bottom: 32px; max-width: 560px; animation: fadeInUp 0.6s ease-out 0.15s both; }
.hero-btns { display: flex; gap: 14px; flex-wrap: wrap; animation: fadeInUp 0.6s ease-out 0.3s both; }

/* ===== 统计数字 ===== */
.stats-bar { background: #fff; padding: 0; border-bottom: 1px solid var(--border); }
.stats-bar .container { display: grid; grid-template-columns: repeat(4, 1fr); }
.stat-item { padding: 32px 20px; text-align: center; border-right: 1px solid #f0f0f0; transition: background 0.3s; }
.stat-item:last-child { border-right: none; }
.stat-item:hover { background: var(--bg-light); }
.stat-item .num { font-size: 2.6rem; font-weight: 700; color: var(--red); line-height: 1; margin-bottom: 8px; }
.stat-item .label { font-size: 13px; color: var(--text-muted); font-weight: 500; letter-spacing: 0.5px; }
.stat-item .unit { font-size: 1.2rem; font-weight: 400; }

/* ===== 区块通用 ===== */
.section { padding: 80px 0; }
.section-alt { background: var(--bg-light); }
.section-header { text-align: center; margin-bottom: 56px; }
.section-header h2 { font-size: 2rem; font-weight: 700; color: var(--bg-dark); margin-bottom: 12px; position: relative; display: inline-block; }
.section-header h2::after { content: ''; display: block; width: 50px; height: 3px; background: var(--red); margin: 14px auto 0; border-radius: 2px; }
.section-header .en-title { font-size: 13px; color: #999; text-transform: uppercase; letter-spacing: 2px; margin-bottom: 6px; }
.section-header p { color: var(--text-muted); font-size: 15px; margin-top: 12px; }

/* ===== 产品卡片 ===== */
.products-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 24px; }
.product-card { background: #fff; border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; transition: all var(--transition); cursor: pointer; }
.product-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-4px); border-color: var(--primary); }
.product-card .img-wrap { height: 200px; overflow: hidden; position: relative; background: #eee; }
.product-card .img-wrap img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.5s; }
.product-card:hover .img-wrap img { transform: scale(1.08); }
.product-card .img-wrap .tag { position: absolute; top: 12px; left: 12px; background: var(--red); color: #fff; font-size: 11px; padding: 3px 10px; border-radius: 3px; font-weight: 500; }
.product-card .card-body { padding: 18px; }
.product-card .cat-label { font-size: 11px; color: var(--primary); font-weight: 600; text-transform: uppercase; letter-spacing: 1px; margin-bottom: 6px; }
.product-card h3 { font-size: 15px; font-weight: 600; margin-bottom: 8px; color: var(--text); }
.product-card p { font-size: 13px; color: var(--text-muted); line-height: 1.5; }
.product-card .card-footer { padding: 12px 18px; border-top: 1px solid #f0f0f0; display: flex; justify-content: space-between; align-items: center; }
.product-card .card-footer .arrow { display: inline-block; transition: transform var(--transition); }
.product-card:hover .card-footer .arrow { transform: translateX(4px); }

/* ===== 案例卡片 ===== */
.cases-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(360px, 1fr)); gap: 28px; }
.case-card { background: #fff; border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; transition: all var(--transition); }
.case-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-4px); }
.case-card .img-wrap { height: 240px; overflow: hidden; position: relative; }
.case-card .img-wrap img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.5s; }
.case-card:hover .img-wrap img { transform: scale(1.06); }
.case-card .img-wrap .overlay { position: absolute; bottom: 0; left: 0; right: 0; background: linear-gradient(transparent, rgba(0,0,0,0.5)); padding: 30px 20px 16px; }
.case-card .img-wrap .overlay .saving { color: #fff; font-weight: 700; font-size: 1.3rem; }
.case-card .card-body { padding: 22px; }
.case-card h3 { font-size: 17px; font-weight: 600; margin-bottom: 10px; color: var(--text); }
.case-card .case-desc { font-size: 13px; color: var(--text-muted); line-height: 1.6; margin-bottom: 14px; }
.case-meta { display: flex; gap: 18px; font-size: 12px; color: #999; flex-wrap: wrap; }
.case-meta span { display: flex; align-items: center; gap: 4px; }

/* ===== 文章卡片 ===== */
.articles-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(340px, 1fr)); gap: 28px; }
.article-card { background: #fff; border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; transition: all var(--transition); }
.article-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-4px); border-color: var(--primary); }
.article-card .img-wrap { height: 200px; overflow: hidden; position: relative; background: #eee; }
.article-card .img-wrap img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.5s; }
.article-card:hover .img-wrap img { transform: scale(1.06); }
.article-card .card-body { padding: 20px; }
.article-card .tag { display: inline-block; font-size: 11px; background: var(--primary-light); color: var(--primary); padding: 2px 10px; border-radius: 3px; margin-bottom: 8px; }
.article-card h3 { font-size: 16px; font-weight: 600; margin: 8px 0; line-height: 1.5; color: var(--text); }
.article-card .read-more { font-size: 13px; color: var(--primary); font-weight: 500; display: inline-flex; align-items: center; gap: 4px; transition: gap var(--transition); }
.article-card:hover .read-more { gap: 8px; }

/* ===== CTA 区块 ===== */
.cta-section { background: linear-gradient(135deg, var(--red) 0%, #f04a3a 100%); color: #fff; padding: 60px 0; text-align: center; position: relative; overflow: hidden; }
.cta-section::before { content: ''; position: absolute; inset: 0; background: radial-gradient(circle at 20% 50%, rgba(255,255,255,0.1) 0%, transparent 50%); }
.cta-section .container { position: relative; z-index: 1; }
.cta-section h2 { font-size: 2rem; font-weight: 700; margin-bottom: 12px; }
.cta-section p { font-size: 16px; opacity: 0.9; margin-bottom: 28px; }
.cta-section .btn-white { display: inline-block; background: #fff; color: var(--red) !important; padding: 14px 36px; border-radius: var(--radius-sm); font-size: 16px; font-weight: 600; transition: all var(--transition); }
.cta-section .btn-white:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,0.2); }
.cta-section .btn-outline-white { display: inline-block; border: 2px solid rgba(255,255,255,0.7); color: #fff !important; padding: 14px 36px; border-radius: var(--radius-sm); font-size: 16px; font-weight: 500; margin-left: 16px; transition: all var(--transition); }
.cta-section .btn-outline-white:hover { background: rgba(255,255,255,0.15); border-color: #fff; }

/* ===== 选型工具 ===== */
.tool-box { background: #fff; border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 40px; max-width: 800px; margin: 0 auto; box-shadow: var(--shadow); }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin-bottom: 20px; }
.form-group label { display: block; font-size: 14px; font-weight: 500; margin-bottom: 8px; color: var(--text); }
.form-group input, .form-group select { width: 100%; padding: 11px 14px; border: 1px solid var(--border); border-radius: var(--radius-sm); font-size: 15px; outline: none; transition: all 0.2s; background: #fff; }
.form-group input:focus, .form-group select:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(26,95,168,0.1); }
.result-box { background: var(--bg-light); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; margin-top: 24px; display: none; animation: fadeIn 0.3s ease-out; }
.result-box.show { display: block; }
.result-item { display: flex; justify-content: space-between; padding: 10px 0; border-bottom: 1px solid var(--border); font-size: 15px; }
.result-item:last-child { border-bottom: none; }
.result-item strong { color: var(--primary); }

/* ===== 联系表单 ===== */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 60px; }
.contact-form { background: #fff; padding: 40px; border-radius: var(--radius-lg); box-shadow: var(--shadow); transition: box-shadow var(--transition); }
.contact-form:hover { box-shadow: var(--shadow-md); }
.contact-form input, .contact-form textarea, .contact-form select { width: 100%; padding: 13px 14px; border: 1px solid var(--border); border-radius: var(--radius-sm); font-size: 15px; margin-bottom: 16px; font-family: inherit; outline: none; transition: all 0.2s; }
.contact-form input:focus, .contact-form textarea:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(26,95,168,0.08); }
.contact-form textarea { height: 150px; resize: vertical; }
.contact-info h3 { font-size: 22px; margin-bottom: 20px; color: var(--bg-dark); }
.contact-info .info-item { display: flex; align-items: flex-start; gap: 12px; margin-bottom: 18px; }
.contact-info .info-icon { width: 36px; height: 36px; background: var(--primary-light); border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: 16px; flex-shrink: 0; }
.contact-info p { color: var(--text-muted); line-height: 1.8; }

/* ===== 内容页 ===== */
.page-banner { background: var(--bg-dark); color: #fff; padding: 56px 0; text-align: center; }
.page-banner h1 { font-size: 34px; font-weight: 700; animation: fadeInUp 0.5s ease-out; }
.page-banner p { font-size: 15px; opacity: 0.75; margin-top: 8px; animation: fadeInUp 0.5s ease-out 0.1s both; }
.breadcrumb { padding: 14px 0; font-size: 13px; color: var(--text-muted); }
.breadcrumb a { color: var(--text-muted); }
.breadcrumb span { margin: 0 6px; }

/* ===== 分页 ===== */
.pagination { text-align: center; padding: 40px 0; }
.pagination ul { display: inline-flex; gap: 6px; }
.pagination li a { display: block; padding: 9px 16px; border: 1px solid var(--border); border-radius: var(--radius-sm); font-size: 14px; transition: all 0.2s; }
.pagination li a:hover { border-color: var(--primary); color: var(--primary); }
.pagination li.active a { background: var(--primary); color: #fff; border-color: var(--primary); }

/* ===== 表格 ===== */
.spec-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.spec-table th { background: var(--bg-dark); color: #fff; padding: 14px 18px; text-align: left; font-weight: 500; }
.spec-table td { padding: 14px 18px; border-bottom: 1px solid var(--border); }
.spec-table tr:hover td { background: var(--bg-light); }
.spec-table tr { transition: background 0.2s; }

/* ===== 消息提示 ===== */
.alert { padding: 14px 18px; border-radius: var(--radius-sm); margin-bottom: 20px; font-size: 14px; animation: fadeIn 0.3s ease-out; }
.alert-success { background: #d4edda; color: #155724; border: 1px solid #c3e6cb; }
.alert-error { background: #f8d7da; color: #721c24; border: 1px solid #f5c6cb; }

/* ===== 页脚 ===== */
.site-footer { background: var(--bg-darker); color: #aaa; padding: 60px 0 0; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }
.footer-col h4 { color: #fff; font-size: 15px; margin-bottom: 16px; font-weight: 600; position: relative; padding-bottom: 12px; }
.footer-col h4::after { content: ''; position: absolute; bottom: 0; left: 0; width: 30px; height: 2px; background: var(--primary); border-radius: 1px; }
.footer-col p, .footer-col li { font-size: 14px; margin-bottom: 10px; line-height: 1.6; }
.footer-col a { color: #999; transition: color 0.2s, padding-left 0.2s; }
.footer-col a:hover { color: #fff; padding-left: 4px; }
.footer-bottom { border-top: 1px solid #2d2d2d; text-align: center; padding: 22px 0; font-size: 13px; color: #777; }

/* ===== 动画关键帧 ===== */
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes fadeInUp { from { opacity: 0; transform: translateY(30px); } to { opacity: 1; transform: translateY(0); } }
@keyframes fadeInLeft { from { opacity: 0; transform: translateX(-30px); } to { opacity: 1; transform: translateX(0); } }
@keyframes fadeInRight { from { opacity: 0; transform: translateX(30px); } to { opacity: 1; transform: translateX(0); } }
@keyframes scaleIn { from { opacity: 0; transform: scale(0.92); } to { opacity: 1; transform: scale(1); } }
@keyframes slideUp { from { opacity: 0; transform: translateY(60px); } to { opacity: 1; transform: translateY(0); } }
@keyframes float { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-8px); } }

/* ===== 滚动动画类 (JS触发) ===== */
.reveal { opacity: 0; }
.reveal.visible { animation: slideUp 0.7s cubic-bezier(0.25, 0.46, 0.45, 0.94) forwards; }
.reveal-delay-1 { animation-delay: 0.1s !important; }
.reveal-delay-2 { animation-delay: 0.2s !important; }
.reveal-delay-3 { animation-delay: 0.3s !important; }
.reveal-delay-4 { animation-delay: 0.4s !important; }
.reveal-fade { opacity: 0; }
.reveal-fade.visible { animation: fadeInUp 0.6s ease-out forwards; }

/* ===== 图片懒加载 ===== */
img[data-src] { opacity: 0; transition: opacity 0.5s; }
img[data-src].loaded { opacity: 1; }

/* ===== 脉动效果 (CTA按钮) ===== */
.pulse { animation: pulse 2s infinite; }
@keyframes pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(231,76,60,0.4); }
  70% { box-shadow: 0 0 0 12px rgba(231,76,60,0); }
}

/* ===== 优势卡片 ===== */
.advantage-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 24px; }
.advantage-card { background: #fff; border: 1px solid var(--border); border-radius: var(--radius); padding: 30px 24px; text-align: center; transition: all var(--transition); }
.advantage-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-4px); border-color: var(--primary); }
.advantage-card .icon { width: 56px; height: 56px; background: var(--primary-light); border-radius: 50%; display: flex; align-items: center; justify-content: center; margin: 0 auto 18px; font-size: 24px; transition: all var(--transition); }
.advantage-card:hover .icon { background: var(--primary); color: #fff; transform: scale(1.1); }
.advantage-card h3 { font-size: 16px; font-weight: 600; margin-bottom: 10px; }
.advantage-card p { font-size: 13px; color: var(--text-muted); }

/* ===== 返顶按钮 ===== */
.back-to-top { position: fixed; bottom: 30px; right: 30px; width: 44px; height: 44px; background: var(--primary); color: #fff; border: none; border-radius: 50%; font-size: 20px; cursor: pointer; z-index: 99; opacity: 0; transform: translateY(20px); transition: all var(--transition); box-shadow: 0 4px 12px rgba(26,95,168,0.3); display: flex; align-items: center; justify-content: center; }
.back-to-top.show { opacity: 1; transform: translateY(0); }
.back-to-top:hover { background: var(--primary-dark); transform: translateY(-4px); }

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .hero h1 { font-size: 30px; }
  .stats-bar .container { grid-template-columns: repeat(2, 1fr); }
  .contact-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .form-row { grid-template-columns: 1fr; }
  .products-grid { grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); }
}
@media (max-width: 768px) {
  .main-nav { display: none; }
  .main-nav.open { display: flex; flex-direction: column; position: absolute; top: 70px; left: 0; right: 0; background: #fff; box-shadow: var(--shadow); padding: 16px; }
  .mobile-menu-btn { display: block; }
  .footer-grid { grid-template-columns: 1fr; }
  .cases-grid, .articles-grid { grid-template-columns: 1fr; }
  .stat-item { border-bottom: 1px solid #f0f0f0; }
  .stat-item:last-child { border-bottom: none; }
}