/* ============ TIANCHENG STEEL site stylesheet ============ */
:root {
  --blue: #0f5fae;
  --blue-dark: #0a3d6d;
  --blue-darker: #072a4a;
  --blue-light: #e8f2fb;
  --accent: #1e88e5;
  --text: #333;
  --muted: #6b7787;
  --border: #e3e8ee;
  --bg-soft: #f5f8fb;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: "Segoe UI", "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
  color: var(--text); background: #fff; line-height: 1.7; font-size: 15px;
}
a { color: var(--blue); text-decoration: none; transition: color .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; }

/* ---------- top bar ---------- */
.topbar { background: var(--blue-darker); color: #cfe2f5; font-size: 13px; }
.topbar .container { display: flex; justify-content: space-between; align-items: center; min-height: 36px; }
.tb-item { margin-right: 18px; white-space: nowrap; }
.topbar-right .lang-switch {
  color: #fff; border: 1px solid rgba(255,255,255,.35); border-radius: 3px;
  padding: 2px 10px; font-size: 12px;
}
.topbar-right .lang-switch:hover { background: var(--blue); border-color: var(--blue); color: #fff; }

/* ---------- header ---------- */
.site-header { background: #fff; box-shadow: 0 2px 8px rgba(7,42,74,.08); position: sticky; top: 0; z-index: 100; }
.header-inner { display: flex; align-items: center; justify-content: space-between; min-height: 74px; }
.logo { display: flex; align-items: center; gap: 12px; }
.logo img { height: 46px; width: auto; }
.logo-text { font-size: 20px; font-weight: 700; color: var(--blue-dark); letter-spacing: .5px; }
.logo-text:hover { color: var(--blue); }
.nav-toggle { display: none; background: none; border: none; font-size: 24px; color: var(--blue-dark); cursor: pointer; }
.main-nav > ul { display: flex; }
.main-nav > ul > li { position: relative; }
.main-nav > ul > li > a {
  display: block; padding: 26px 16px; color: var(--blue-dark);
  font-size: 15px; font-weight: 600; position: relative;
}
.main-nav > ul > li > a::after {
  content: ""; position: absolute; left: 16px; right: 16px; bottom: 18px;
  height: 3px; background: var(--blue); border-radius: 2px;
  transform: scaleX(0); transition: transform .25s;
}
.main-nav > ul > li > a:hover, .main-nav > ul > li > a.active { color: var(--blue); }
.main-nav > ul > li > a:hover::after, .main-nav > ul > li > a.active::after { transform: scaleX(1); }
.dropdown {
  position: absolute; top: 100%; left: 0; min-width: 180px; background: #fff;
  box-shadow: 0 8px 24px rgba(7,42,74,.15); border-top: 3px solid var(--blue);
  opacity: 0; visibility: hidden; transform: translateY(8px); transition: all .2s; z-index: 99;
}
.main-nav > ul > li:hover .dropdown { opacity: 1; visibility: visible; transform: translateY(0); }
.dropdown li a { display: block; padding: 10px 18px; color: var(--text); font-size: 14px; white-space: nowrap; }
.dropdown li a:hover { background: var(--blue-light); color: var(--blue); }

/* ---------- banner slider ---------- */
.banner { position: relative; overflow: hidden; background: var(--blue-darker); }
.banner-slide {
  display: none; position: relative; height: 460px;
  background-size: cover; background-position: center;
}
.banner-slide.active { display: block; animation: fadeIn .6s; }
@keyframes fadeIn { from { opacity: .4; } to { opacity: 1; } }
.banner-slide::after {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(100deg, rgba(7,42,74,.82) 0%, rgba(7,42,74,.45) 55%, rgba(7,42,74,.1) 100%);
}
.banner-caption {
  position: absolute; z-index: 2; left: 50%; top: 50%; transform: translate(-50%,-50%);
  width: 1200px; max-width: calc(100% - 40px); color: #fff;
}
.banner-caption h2 { font-size: 42px; font-weight: 700; line-height: 1.25; margin-bottom: 14px; text-shadow: 0 2px 12px rgba(0,0,0,.3); }
.banner-caption p { font-size: 17px; max-width: 620px; margin-bottom: 26px; opacity: .92; }
.banner-btn {
  display: inline-block; background: var(--blue); color: #fff; padding: 12px 34px;
  border-radius: 4px; font-size: 15px; font-weight: 600; border: 2px solid var(--blue);
}
.banner-btn:hover { background: transparent; color: #fff; border-color: #fff; }
.banner-dots { position: absolute; bottom: 26px; left: 50%; transform: translateX(-50%); display: flex; gap: 10px; z-index: 3; }
.banner-dots span { width: 12px; height: 12px; border-radius: 50%; background: rgba(255,255,255,.45); cursor: pointer; transition: all .2s; }
.banner-dots span.active { background: #fff; transform: scale(1.15); }

/* ---------- sections ---------- */
.section { padding: 64px 0; }
.section.alt { background: var(--bg-soft); }
.section-head { text-align: center; margin-bottom: 44px; }
.section-head h2 { font-size: 30px; color: var(--blue-dark); font-weight: 700; }
.section-head h2 span { color: var(--blue); }
.section-head .sub { color: var(--muted); font-size: 14px; letter-spacing: 2px; text-transform: uppercase; margin-top: 6px; }
.section-head::after {
  content: ""; display: block; width: 56px; height: 4px; background: var(--blue);
  border-radius: 2px; margin: 16px auto 0;
}

/* about block */
.about-wrap { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: center; }
.about-img { border-radius: 8px; overflow: hidden; box-shadow: 0 10px 30px rgba(7,42,74,.12); }
.about-text h3 { font-size: 24px; color: var(--blue-dark); margin-bottom: 16px; }
.about-text p { color: #4a5568; margin-bottom: 14px; text-align: justify; }
.about-feats { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 20px; }
.about-feats li { padding-left: 24px; position: relative; color: var(--text); font-weight: 500; }
.about-feats li::before { content: "✓"; position: absolute; left: 0; color: var(--blue); font-weight: 700; }

/* stats strip */
.stats { background: linear-gradient(90deg, var(--blue-dark), var(--blue)); color: #fff; padding: 40px 0; }
.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); text-align: center; }
.stats-grid .num { font-size: 36px; font-weight: 700; }
.stats-grid .lbl { font-size: 14px; opacity: .85; margin-top: 4px; }

/* product cards */
.prod-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 28px; }
.prod-card {
  background: #fff; border: 1px solid var(--border); border-radius: 8px; overflow: hidden;
  transition: all .25s; display: flex; flex-direction: column;
}
.prod-card:hover { box-shadow: 0 14px 34px rgba(7,42,74,.14); transform: translateY(-5px); border-color: transparent; }
.prod-card .thumb { height: 190px; background: var(--blue-light); display: flex; align-items: center; justify-content: center; overflow: hidden; }
.prod-card .thumb img { width: 100%; height: 100%; object-fit: cover; }
.prod-card .body { padding: 20px 22px 24px; flex: 1; display: flex; flex-direction: column; }
.prod-card h3 { font-size: 18px; color: var(--blue-dark); margin-bottom: 4px; }
.prod-card .en { color: var(--muted); font-size: 13px; margin-bottom: 10px; }
.prod-card p { color: #4a5568; font-size: 14px; flex: 1; }
.prod-card .more { margin-top: 14px; font-weight: 600; font-size: 14px; }
.prod-card .more::after { content: " →"; }

/* advantages */
.adv-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 26px; }
.adv-card { background: #fff; border-radius: 8px; padding: 34px 24px; text-align: center; border: 1px solid var(--border); transition: all .25s; }
.adv-card:hover { box-shadow: 0 12px 30px rgba(7,42,74,.12); transform: translateY(-4px); }
.adv-card .icon {
  width: 72px; height: 72px; margin: 0 auto 18px; border-radius: 50%;
  background: var(--blue-light); display: flex; align-items: center; justify-content: center;
}
.adv-card .icon img { width: 40px; height: 40px; }
.adv-card h3 { font-size: 17px; color: var(--blue-dark); margin-bottom: 8px; }
.adv-card p { font-size: 13.5px; color: var(--muted); }

/* applications strip */
.app-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; }
.app-card { position: relative; border-radius: 8px; overflow: hidden; height: 240px; color: #fff; }
.app-card img { width: 100%; height: 100%; object-fit: cover; }
.app-card::after { content: ""; position: absolute; inset: 0; background: linear-gradient(180deg, rgba(7,42,74,0) 30%, rgba(7,42,74,.85) 100%); }
.app-card .txt { position: absolute; z-index: 2; left: 20px; right: 20px; bottom: 18px; }
.app-card .txt h3 { font-size: 18px; }
.app-card .txt p { font-size: 13px; opacity: .9; }

/* news */
.news-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 28px; }
.news-card { background: #fff; border-radius: 8px; overflow: hidden; border: 1px solid var(--border); transition: all .25s; }
.news-card:hover { box-shadow: 0 12px 30px rgba(7,42,74,.12); transform: translateY(-4px); }
.news-card .thumb { height: 170px; background: var(--blue-light); overflow: hidden; }
.news-card .thumb img { width: 100%; height: 100%; object-fit: cover; }
.news-card .body { padding: 18px 20px 22px; }
.news-card .date { color: var(--blue); font-size: 13px; font-weight: 600; margin-bottom: 8px; }
.news-card h3 { font-size: 16.5px; color: var(--blue-dark); margin-bottom: 8px; line-height: 1.5; }
.news-card p { color: var(--muted); font-size: 13.5px; }

/* CTA */
.cta { background: linear-gradient(100deg, var(--blue-dark), var(--blue)); color: #fff; padding: 56px 0; text-align: center; }
.cta h2 { font-size: 28px; margin-bottom: 12px; }
.cta p { opacity: .9; margin-bottom: 26px; }
.cta .banner-btn { background: #fff; color: var(--blue-dark); border-color: #fff; }
.cta .banner-btn:hover { background: transparent; color: #fff; }

/* ---------- sub page banner ---------- */
.page-banner {
  background: linear-gradient(100deg, var(--blue-darker), var(--blue));
  color: #fff; padding: 64px 0; text-align: center;
}
.page-banner h1 { font-size: 34px; font-weight: 700; }
.page-banner .crumb { margin-top: 10px; font-size: 13.5px; opacity: .85; }
.page-banner .crumb a { color: #fff; text-decoration: underline; }

/* ---------- content ---------- */
.page-layout { display: grid; grid-template-columns: 250px 1fr; gap: 40px; align-items: start; }
.side-box { background: #fff; border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }
.side-box .side-title {
  background: var(--blue); color: #fff; padding: 14px 20px; font-size: 16px; font-weight: 600;
}
.side-box ul { padding: 8px 0; }
.side-box li a { display: block; padding: 11px 22px; color: var(--text); border-left: 3px solid transparent; font-size: 14.5px; }
.side-box li a:hover, .side-box li a.active { background: var(--blue-light); color: var(--blue); border-left-color: var(--blue); }
.side-contact { margin-top: 24px; background: var(--blue-darker); color: #cfe2f5; border-radius: 8px; padding: 22px; font-size: 14px; }
.side-contact h4 { color: #fff; margin-bottom: 12px; font-size: 16px; }
.side-contact p { margin-bottom: 8px; }

.content-box { background: #fff; border: 1px solid var(--border); border-radius: 8px; padding: 36px 40px; min-height: 400px; }
.content-box h1.page-title { font-size: 24px; color: var(--blue-dark); margin-bottom: 20px; padding-bottom: 16px; border-bottom: 2px solid var(--blue-light); }
.prose h2 { font-size: 20px; color: var(--blue-dark); margin: 26px 0 12px; }
.prose h3 { font-size: 17px; color: var(--blue-dark); margin: 20px 0 10px; }
.prose p { margin-bottom: 12px; color: #3d4852; text-align: justify; }
.prose ul, .prose ol { margin: 0 0 14px 22px; }
.prose li { margin-bottom: 6px; color: #3d4852; }
.prose strong { color: var(--blue-dark); }
.prose table { width: 100%; border-collapse: collapse; margin: 14px 0 20px; font-size: 14px; }
.prose th, .prose td { border: 1px solid var(--border); padding: 9px 14px; text-align: left; }
.prose th { background: var(--blue-light); color: var(--blue-dark); font-weight: 600; }
.prose img { border-radius: 6px; margin: 10px 0; }
.prose blockquote { border-left: 4px solid var(--blue); background: var(--bg-soft); padding: 14px 18px; margin: 14px 0; color: #4a5568; }

/* product detail */
.prod-hero { display: grid; grid-template-columns: 5fr 7fr; gap: 34px; margin-bottom: 30px; }
.prod-gallery { display: flex; flex-direction: column; gap: 10px; }
.prod-gallery .img { background: var(--blue-light); border-radius: 8px; overflow: hidden; min-height: 300px; display: flex; align-items: center; justify-content: center; }
.prod-gallery .img img { width: 100%; height: 100%; object-fit: cover; }
.prod-gallery .thumbs { display: flex; flex-wrap: wrap; gap: 8px; }
.prod-gallery .thumbs img {
  width: 72px; height: 54px; object-fit: cover; border-radius: 4px; cursor: pointer;
  border: 2px solid transparent; opacity: .75; transition: all .15s;
}
.prod-gallery .thumbs img:hover { opacity: 1; }
.prod-gallery .thumbs img.on { border-color: var(--blue); opacity: 1; }
.prod-hero .info h1 { font-size: 24px; color: var(--blue-dark); margin-bottom: 6px; }
.prod-hero .info .en { color: var(--muted); margin-bottom: 14px; }
.prod-hero .info .desc { color: #4a5568; margin-bottom: 18px; }
.spec-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.spec-table th, .spec-table td { border: 1px solid var(--border); padding: 9px 14px; }
.spec-table th { background: var(--blue-light); color: var(--blue-dark); width: 130px; font-weight: 600; text-align: left; }
.prod-nav { display: flex; justify-content: space-between; margin-top: 30px; padding-top: 20px; border-top: 1px solid var(--border); font-size: 14px; }

/* news list */
.news-list-item { display: grid; grid-template-columns: 210px 1fr; gap: 26px; padding: 24px 0; border-bottom: 1px solid var(--border); }
.news-list-item:first-child { padding-top: 0; }
.news-list-item .thumb { height: 140px; border-radius: 6px; overflow: hidden; background: var(--blue-light); }
.news-list-item .thumb img { width: 100%; height: 100%; object-fit: cover; }
.news-list-item .meta { color: var(--muted); font-size: 13px; margin-bottom: 8px; }
.news-list-item .meta .cat { color: var(--blue); font-weight: 600; }
.news-list-item h2 { font-size: 18px; color: var(--blue-dark); margin-bottom: 8px; }
.news-list-item h2 a { color: inherit; }
.news-list-item h2 a:hover { color: var(--blue); }
.news-list-item p { color: var(--muted); font-size: 14px; }
.pagination { display: flex; justify-content: center; gap: 8px; margin-top: 34px; }
.pagination a, .pagination span {
  min-width: 38px; height: 38px; display: inline-flex; align-items: center; justify-content: center;
  border: 1px solid var(--border); border-radius: 4px; color: var(--text); font-size: 14px; padding: 0 10px;
}
.pagination a:hover { border-color: var(--blue); color: var(--blue); }
.pagination .current { background: var(--blue); border-color: var(--blue); color: #fff; }

/* contact */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; }
.contact-info-card { background: var(--blue-darker); color: #cfe2f5; border-radius: 8px; padding: 34px; }
.contact-info-card h3 { color: #fff; font-size: 20px; margin-bottom: 20px; }
.contact-info-card .row { display: flex; gap: 14px; margin-bottom: 18px; }
.contact-info-card .row .ico {
  width: 42px; height: 42px; flex: none; border-radius: 50%; background: rgba(255,255,255,.12);
  display: flex; align-items: center; justify-content: center; font-size: 18px;
}
.contact-info-card .row .val { padding-top: 2px; }
.contact-info-card .row .val b { display: block; color: #fff; font-size: 15px; }
.contact-info-card .row .val span { font-size: 14px; }
.form-card { background: #fff; border: 1px solid var(--border); border-radius: 8px; padding: 34px; }
.form-card h3 { font-size: 20px; color: var(--blue-dark); margin-bottom: 20px; }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.form-group { margin-bottom: 16px; }
.form-group label { display: block; font-size: 14px; color: var(--text); margin-bottom: 6px; font-weight: 500; }
.form-group input, .form-group select, .form-group textarea {
  width: 100%; border: 1px solid var(--border); border-radius: 4px; padding: 10px 14px;
  font-size: 14px; font-family: inherit; transition: border-color .2s; background: #fff; color: var(--text);
}
.form-group input:focus, .form-group select:focus, .form-group textarea:focus { outline: none; border-color: var(--blue); }
.form-group textarea { min-height: 120px; resize: vertical; }
.btn {
  display: inline-block; background: var(--blue); color: #fff; border: none; cursor: pointer;
  padding: 12px 36px; border-radius: 4px; font-size: 15px; font-weight: 600; font-family: inherit;
}
.btn:hover { background: var(--blue-dark); color: #fff; }
.btn-block { width: 100%; }
.alert { padding: 12px 18px; border-radius: 4px; margin-bottom: 18px; font-size: 14px; }
.alert-success { background: #e6f6ec; color: #157347; border: 1px solid #b7e4c7; }
.alert-error { background: #fdecea; color: #b02a37; border: 1px solid #f5c2c7; }

/* search */
.search-box { display: flex; gap: 12px; margin-bottom: 30px; }
.search-box input { flex: 1; border: 1px solid var(--border); border-radius: 4px; padding: 12px 16px; font-size: 15px; }
.search-box .btn { padding: 12px 28px; }

/* 404 */
.notfound { text-align: center; padding: 90px 0; }
.notfound .code { font-size: 90px; font-weight: 700; color: var(--blue); line-height: 1; }
.notfound p { color: var(--muted); margin: 14px 0 26px; }

/* ---------- footer ---------- */
.site-footer { background: var(--blue-darker); color: #b8cfe4; margin-top: 0; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1.2fr; gap: 40px; padding: 56px 20px 40px; }
.footer-logo { height: 42px; width: auto; margin-bottom: 16px; background: #fff; border-radius: 4px; padding: 4px 8px; }
.footer-col h4 { color: #fff; font-size: 16px; margin-bottom: 18px; position: relative; padding-bottom: 10px; }
.footer-col h4::after { content: ""; position: absolute; left: 0; bottom: 0; width: 34px; height: 3px; background: var(--blue); border-radius: 2px; }
.footer-col p { font-size: 13.5px; line-height: 1.8; }
.footer-col ul li { margin-bottom: 9px; font-size: 13.5px; }
.footer-col ul li a { color: #b8cfe4; }
.footer-col ul li a:hover { color: #fff; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,.1); padding: 18px 0; font-size: 13px; }
.footer-bottom .container { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; }
.footer-bottom p { opacity: .8; }
.tech-support a { color: #ffd75e; font-weight: 600; }
.tech-support a:hover { color: #fff; }

/* ---------- responsive ---------- */
@media (max-width: 1024px) {
  .prod-grid, .news-grid { grid-template-columns: repeat(2, 1fr); }
  .adv-grid, .app-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .page-layout { grid-template-columns: 1fr; }
  .side-box { display: none; }
}
@media (max-width: 768px) {
  .nav-toggle { display: block; }
  .main-nav { display: none; position: absolute; top: 100%; left: 0; right: 0; background: #fff; box-shadow: 0 10px 24px rgba(7,42,74,.15); }
  .main-nav.open { display: block; }
  .main-nav > ul { flex-direction: column; }
  .main-nav > ul > li > a { padding: 14px 20px; border-top: 1px solid var(--border); }
  .main-nav > ul > li > a::after { display: none; }
  .dropdown { position: static; opacity: 1; visibility: visible; transform: none; box-shadow: none; border-top: none; display: none; }
  .main-nav > ul > li:hover .dropdown, .main-nav > ul > li.open .dropdown { display: block; }
  .banner-slide { height: 340px; }
  .banner-caption h2 { font-size: 26px; }
  .banner-caption p { font-size: 14px; }
  .about-wrap, .contact-grid, .prod-hero { grid-template-columns: 1fr; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 20px; }
  .prod-grid, .news-grid, .adv-grid, .app-grid { grid-template-columns: 1fr; }
  .news-list-item { grid-template-columns: 1fr; }
  .form-row { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: 28px; }
  .topbar .tb-item:nth-child(3) { display: none; }
  .content-box { padding: 24px 20px; }
}