:root {
  --primary: #123a63;   /* 主色 */
  --accent: #f0b429;    /* 强调/点缀 */
  --dark: #0e2c4d;      /* 深色 */
  --brand: #c0392b;     /* 品牌红 */
}
/* 城市站群系统 - 前台样式 */
* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: "PingFang SC","Microsoft YaHei","Helvetica Neue",Arial,sans-serif; color: #333; line-height: 1.7; background: #fff; -webkit-font-smoothing: antialiased; overflow-x: clip; }
a { color: inherit; text-decoration: none; }
.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* 顶部信息条 */
.topbar { background: var(--primary); color: #fff; font-size: 13px; }
.topbar-inner { display: flex; align-items: center; justify-content: space-between; height: 40px; }
.topbar-phone { font-weight: 700; letter-spacing: .5px; }
.topbar-switch select { margin-left: 6px; padding: 2px 6px; border: none; border-radius: 3px; }

/* 页头 */
.site-header { background: #fff; border-bottom: 1px solid #eef1f5; position: -webkit-sticky; position: sticky; top: 0; z-index: 50; }
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 72px; position: relative; }
.logo { font-size: 24px; font-weight: 800; color: var(--primary); display: flex; align-items: baseline; gap: 10px; }
.logo small { font-size: 12px; font-weight: 400; color: #8a97a8; letter-spacing: 1px; }
.nav { display: flex; gap: 28px; }
.nav a { font-size: 15px; color: #444; padding: 8px 0; border-bottom: 2px solid transparent; transition: .2s; }
.nav a:hover, .nav a.active { color: var(--brand); border-bottom-color: var(--brand); }
/* 移动端汉堡菜单按钮（默认隐藏，<=768 显示） */
.nav-toggle { display: none; background: none; border: 1px solid #d7dee8; color: var(--primary); font-size: 20px; width: 40px; height: 40px; border-radius: 8px; cursor: pointer; line-height: 1; }

/* Hero */
.hero { background: linear-gradient(135deg, #14507c 0%, var(--primary) 60%, var(--dark) 100%); color: #fff; padding: 64px 0 72px; }
.hero-badge { display: inline-block; background: rgba(255,255,255,.12); border: 1px solid rgba(255,255,255,.25); padding: 4px 14px; border-radius: 20px; font-size: 13px; margin-bottom: 18px; letter-spacing: 1px; }
.hero-title { font-size: 44px; font-weight: 800; margin-bottom: 8px; }
.hero-title span { color: var(--accent); }
.hero-sub { font-size: 20px; color: #cfe0ef; margin-bottom: 16px; letter-spacing: 1px; }
.hero-desc { max-width: 760px; color: #d5e2ee; font-size: 15px; margin-bottom: 24px; }
.hero-features { display: flex; flex-wrap: wrap; gap: 10px; margin-bottom: 28px; }
.hero-features span { background: rgba(255,255,255,.1); padding: 5px 14px; border-radius: 16px; font-size: 13px; }
.hero-call { display: inline-block; background: var(--accent); color: var(--primary); font-size: 20px; font-weight: 800; padding: 12px 34px; border-radius: 30px; box-shadow: 0 6px 20px rgba(0,0,0,.25); transition: .2s; }
.hero-call:hover { transform: translateY(-2px); }

/* 通用区块 */
section { padding: 56px 0; }
.section-title { font-size: 28px; font-weight: 700; color: var(--primary); text-align: center; margin-bottom: 10px; }
.section-sub { text-align: center; color: #7a8798; margin-bottom: 36px; }

/* 关于 */
.about { background: #f7f9fc; }
.about p { margin-bottom: 14px; color: #45505e; text-align: justify; }
.about-call { text-align: center; font-size: 18px; margin-top: 20px; }
.about-call a { color: var(--brand); font-weight: 700; font-size: 22px; }
.about-service { text-align: center; background: #fff; border: 1px solid #e4e9f0; border-radius: 8px; padding: 10px; }

/* 产品 */
.series { margin-bottom: 40px; }
.series-head { display: flex; align-items: center; gap: 10px; margin-bottom: 18px; }
.series-icon { font-size: 22px; width: 44px; height: 44px; display: flex; align-items: center; justify-content: center; background: var(--primary); color: #fff; border-radius: 10px; }
.series-head h3 { font-size: 20px; color: var(--primary); }
.series-head em { font-style: normal; font-size: 12px; color: #fff; background: var(--accent); padding: 2px 10px; border-radius: 12px; }
.series-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 18px; }
.product-card { border: 1px solid #e9edf3; border-radius: 12px; padding: 22px 18px; text-align: center; transition: .2s; background: #fff; }
.product-card:hover { box-shadow: 0 8px 24px rgba(18,58,99,.12); transform: translateY(-3px); border-color: #cfe0ef; }
.product-name { font-size: 16px; font-weight: 600; color: var(--primary); margin-bottom: 6px; }
.product-cat { font-size: 12px; color: #8a97a8; }

/* 友情链接 */
.links { background: #f7f9fc; }
.link-groups { display: grid; grid-template-columns: 1fr 1fr; gap: 30px; }
.link-group h4 { font-size: 15px; color: var(--primary); margin-bottom: 14px; padding-left: 10px; border-left: 3px solid var(--accent); }
.link-list { display: flex; flex-wrap: wrap; gap: 10px; }
.link-list a { font-size: 13px; color: #55647a; background: #fff; border: 1px solid #e4e9f0; padding: 5px 12px; border-radius: 16px; transition: .2s; }
.link-list a:hover { color: var(--brand); border-color: var(--brand); }

/* 页脚 */
.site-footer { background: var(--dark); color: #b9c9da; text-align: center; padding: 34px 0; }
.footer-brand { font-size: 18px; font-weight: 700; color: #fff; margin-bottom: 6px; }
.footer-phone a { color: var(--accent); font-size: 18px; font-weight: 700; }
.footer-copy { font-size: 13px; margin-top: 10px; opacity: .8; }
.footer-ops { margin-top: 12px; display: flex; gap: 24px; justify-content: center; font-size: 13px; }
.footer-ops a:hover { color: var(--accent); }

/* 底部浮动条 */
.float-bar { position: fixed; left: 0; right: 0; bottom: 0; background: var(--brand); color: #fff; text-align: center; z-index: 40; display: none; }
.float-bar a { display: block; padding: 12px; font-size: 16px; font-weight: 700; color: #fff; }

/* 弹窗 */
.modal { display: none; position: fixed; inset: 0; background: rgba(0,0,0,.5); z-index: 100; align-items: center; justify-content: center; padding: 20px; }
.modal-box { background: #fff; border-radius: 12px; width: 100%; max-width: 420px; overflow: hidden; }
.modal-head { display: flex; align-items: center; justify-content: space-between; background: var(--primary); color: #fff; padding: 14px 18px; font-size: 16px; font-weight: 600; }
.modal-close { background: none; border: none; color: #fff; font-size: 22px; cursor: pointer; line-height: 1; }
.modal-form { padding: 18px; }
.modal-tip { font-size: 15px; font-weight: 600; color: var(--primary); }
.modal-sub { font-size: 13px; color: #7a8798; margin: 6px 0 16px; }
.modal-form label { display: block; margin-bottom: 14px; font-size: 14px; color: #45505e; }
.modal-form input, .modal-form select, .modal-form textarea { width: 100%; margin-top: 6px; padding: 9px 12px; border: 1px solid #d7dee8; border-radius: 6px; font-size: 14px; font-family: inherit; }
.modal-form input:focus, .modal-form textarea:focus, .modal-form select:focus { outline: none; border-color: var(--primary); }
.btn { width: 100%; background: var(--accent); color: var(--primary); border: none; padding: 12px; border-radius: 6px; font-size: 16px; font-weight: 700; cursor: pointer; }
.btn:hover { background: #e2a51f; }

/* 提示 */
.toast { position: fixed; top: 20px; left: 50%; transform: translateX(-50%); background: var(--primary); color: #fff; padding: 12px 24px; border-radius: 8px; z-index: 200; box-shadow: 0 6px 20px rgba(0,0,0,.3); transition: opacity .6s; }

/* ============ 产品图 ============ */
.product-img { width: 280px; height: 280px; max-width: 100%; margin: 0 auto 12px; border-radius: 8px; overflow: hidden; background: #f4f6f9; display: flex; align-items: center; justify-content: center; }
.product-img img { width: 100%; height: 100%; object-fit: cover; }
.product-img-ph { font-size: 40px; opacity: .5; }


/* 响应式 */
@media (max-width: 768px) {
  .container { padding: 0 14px; }
  .topbar-inner { height: auto; flex-wrap: wrap; gap: 4px; padding: 6px 0; font-size: 12px; }
  .topbar-phone { font-size: 12px; }
  .nav { display: none; }
  .nav-toggle { display: block; }
  /* 汉堡展开下拉菜单 */
  .nav.open {
    display: flex; flex-direction: column; position: absolute; top: 56px; left: 0; right: 0;
    background: #fff; border-bottom: 1px solid #eef1f5; box-shadow: 0 8px 20px rgba(0,0,0,.08); padding: 8px 14px; gap: 0; z-index: 60;
  }
  .nav.open a { padding: 12px 6px; border-bottom: 1px solid #f0f3f7; font-size: 15px; }
  .nav.open a:last-child { border-bottom: none; }
  .nav.open a.active { color: var(--brand); border-left: 3px solid var(--brand); padding-left: 12px; }
  .header-inner { height: 56px; }
  .logo { font-size: 19px; gap: 6px; }
  .logo small { font-size: 10px; }
  /* Hero */
  .hero { padding: 40px 0 46px; }
  .hero-title { font-size: 25px; line-height: 1.3; }
  .hero-sub { font-size: 15px; }
  .hero-desc { font-size: 14px; margin-bottom: 16px; }
  .hero-features span { font-size: 12px; padding: 4px 10px; }
  .hero-call { font-size: 17px; padding: 10px 24px; }
  /* 区块 */
  section { padding: 38px 0; }
  .section-title { font-size: 22px; }
  .section-sub { margin-bottom: 24px; font-size: 14px; }
  /* 产品 */
  .series { margin-bottom: 28px; }
  .series-head h3 { font-size: 17px; }
  .series-icon { width: 36px; height: 36px; font-size: 17px; }
  .series-grid { grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 12px; }
  .product-card { padding: 12px 10px; }
  .product-name { font-size: 13px; }
  .product-cat { font-size: 11px; }
  .series-grid .product-img { width: 100% !important; height: auto !important; aspect-ratio: 1/1; max-width: none !important; }
  .series-grid .product-img img { object-fit: contain !important; max-width: 100% !important; height: auto !important; }
  .series-grid .product-img-ph { font-size: 30px; }
  /* 友链 */
  .link-groups { grid-template-columns: 1fr; gap: 20px; }
  /* FAQ */
  .faq-item { padding: 14px 16px; }
  .faq-q { font-size: 14px; }
  /* 浮动电话 */
  .float-bar { display: block; }
  body { padding-bottom: 48px; }
}
@media (max-width: 480px) {
  .series-grid { grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); }
  .topbar-switch select { max-width: 120px; }
}

/* ============ FAQ 区块 ============ */
.faq { background: #fff; }
.faq-list { max-width: 860px; margin: 0 auto; }
.faq-item { border: 1px solid #e9edf3; border-radius: 10px; padding: 18px 22px; margin-bottom: 14px; background: #fff; transition: .2s; }
.faq-item:hover { box-shadow: 0 4px 16px rgba(0,0,0,.06); border-color: var(--primary); }
.faq-q { font-size: 16px; font-weight: 700; color: var(--primary); margin-bottom: 8px; }
.faq-a { font-size: 14px; color: #55647a; line-height: 1.8; }