:root {
  --primary: #0B4F8A;
  --primary-dark: #083A66;
  --accent: #2BB673;
  --text: #333;
  --muted: #666;
  --bg: #fff;
  --light: #F4F7FA;
  --border: #E3E8EE;
  --max: 1200px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
  color: var(--text);
  line-height: 1.7;
  background: var(--bg);
}

img { max-width: 100%; display: block; }
a { color: var(--primary); text-decoration: none; }

.container { max-width: var(--max); margin: 0 auto; padding: 0 20px; }
section { padding: 56px 0; }

.section-title { font-size: 28px; color: var(--primary); text-align: center; margin-bottom: 8px; }
.section-sub { text-align: center; color: var(--muted); margin-bottom: 36px; }

/* 头部导航 */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: #fff; border-bottom: 1px solid var(--border);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.logo { display: flex; align-items: center; gap: 10px; }
.logo img { height: 36px; width: auto; }
.logo span { font-weight: 700; color: var(--primary); font-size: 15px; }
.site-nav { display: flex; gap: 24px; align-items: center; }
.site-nav a { color: var(--text); font-size: 15px; }
.site-nav a.active, .site-nav a:hover { color: var(--primary); font-weight: 600; }
.lang-switch { border: 1px solid var(--primary); border-radius: 4px; padding: 2px 10px; }
.nav-toggle { display: none; background: none; border: none; font-size: 24px; color: var(--primary); cursor: pointer; }

/* 首页 Hero（图片路径相对本 CSS 文件） */
.hero {
  background: linear-gradient(rgba(8, 58, 102, 0.6), rgba(8, 58, 102, 0.6)),
    url("../images/hero-steel-coils.jpg") center / cover no-repeat;
  color: #fff; text-align: center; padding: 120px 20px;
}
.hero h1 { font-size: 38px; margin-bottom: 14px; }
.hero p { font-size: 18px; margin-bottom: 28px; }
.btn { display: inline-block; padding: 12px 28px; border-radius: 4px; font-size: 16px; margin: 0 6px; }
.btn-primary { background: var(--accent); color: #fff; }
.btn-outline { border: 2px solid #fff; color: #fff; }

/* 子页面横幅 */
.page-banner { background: var(--primary); color: #fff; text-align: center; padding: 56px 20px; }
.page-banner h1 { font-size: 30px; }

/* 卡片 */
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.card { border: 1px solid var(--border); border-radius: 8px; overflow: hidden; background: #fff; transition: box-shadow 0.2s; }
.card:hover { box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1); }
.card img { height: 200px; width: 100%; object-fit: cover; }
.card-body { padding: 20px; }
.card-body h3 { color: var(--primary); margin-bottom: 8px; font-size: 18px; }

/* 图片墙 */
.gallery { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.gallery a { display: block; }
.gallery img { height: 220px; width: 100%; object-fit: cover; border-radius: 6px; }

/* 产品分区 */
.product-section { padding: 48px 0; border-bottom: 1px solid var(--border); }
.product-section h2 { color: var(--primary); font-size: 24px; margin-bottom: 12px; }
.product-section .desc { max-width: 760px; margin-bottom: 24px; }

/* 出口市场 */
.markets { background: var(--light); }
.market-list { display: flex; flex-wrap: wrap; gap: 12px; justify-content: center; }
.market-list span { background: #fff; border: 1px solid var(--border); border-radius: 20px; padding: 6px 18px; font-size: 14px; }

/* 底部 CTA 与页脚 */
.cta { background: var(--primary); color: #fff; text-align: center; }
.cta h2 { margin-bottom: 10px; font-size: 26px; }
.cta p { margin-bottom: 22px; }
.site-footer { background: var(--primary-dark); color: #cfe0ef; padding: 36px 0; font-size: 14px; }
.footer-inner { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 16px; }
.site-footer a { color: #fff; }

/* 关于我们 */
.about-content p { margin-bottom: 16px; max-width: 860px; }

/* 联系方式 */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 32px; }
.contact-item { margin-bottom: 18px; }
.contact-item strong { color: var(--primary); display: block; margin-bottom: 4px; }

/* Lightbox */
.lightbox-overlay {
  display: none; position: fixed; inset: 0; z-index: 200;
  background: rgba(0, 0, 0, 0.85); align-items: center; justify-content: center; cursor: zoom-out;
}
.lightbox-overlay.open { display: flex; }
.lightbox-overlay img { max-width: 92%; max-height: 90%; border-radius: 6px; }

/* 移动端 */
@media (max-width: 768px) {
  .nav-toggle { display: block; }
  .site-nav {
    display: none; position: absolute; top: 64px; left: 0; right: 0;
    background: #fff; flex-direction: column; align-items: flex-start;
    padding: 16px 20px; border-bottom: 1px solid var(--border); gap: 12px;
  }
  .site-nav.open { display: flex; }
  .cards, .gallery, .contact-grid { grid-template-columns: 1fr; }
  .hero { padding: 72px 20px; }
  .hero h1 { font-size: 26px; }
  section { padding: 40px 0; }
}

/* 暗色主题（跟随系统 prefers-color-scheme） */
@media (prefers-color-scheme: dark) {
  :root {
    --text: #E2E8F0;
    --muted: #9AA7B4;
    --bg: #14181D;
    --light: #1B222B;
    --border: #2C3846;
    --primary-light: #6BA3D8;
  }
  a { color: var(--primary-light); }
  .site-header { background: var(--light); border-bottom-color: var(--border); }
  .logo span { color: var(--primary-light); }
  .site-nav { background: var(--light); }
  .site-nav a { color: var(--text); }
  .site-nav a.active, .site-nav a:hover { color: var(--primary-light); }
  .nav-toggle { color: var(--primary-light); }
  .lang-switch { border-color: var(--primary-light); color: var(--primary-light); }
  .section-title, .product-section h2, .card-body h3, .contact-item strong { color: var(--primary-light); }
  .card, .market-list span { background: var(--light); border-color: var(--border); }
  .product-section { border-bottom-color: var(--border); }
  /* Hero/页脚/CTA 为深蓝底白字，暗色下保持不变 */
}