/* ============================================================
   汇达 HUIDA · B2B 工程机械配件与滤清器目录站（中文版原型）
   设计基调：沉稳工业蓝 / 深灰 / 安全橙点缀 · 工业实用风
   ============================================================ */

:root {
  /* 品牌色板 */
  --blue-950: #071F38;
  --blue-900: #0A2E52;
  --blue-800: #0C447C;   /* 主品牌蓝 */
  --blue-600: #155A9C;
  --blue-100: #E3ECF4;
  --blue-050: #F0F5FA;
  --ink:       #1B2A3A;  /* 深灰正文 */
  --steel:     #5A6B7B;  /* 次级灰 */
  --steel-400: #8494A3;
  --line:      #D9E0E7;
  --bg:        #F4F6F9;
  --accent:      #F0821E; /* 安全橙 */
  --accent-dark: #C96A12;
  --ok:        #1E7F4F;
  --white:     #FFFFFF;

  /* 字体 */
  --sans: "Microsoft YaHei", "PingFang SC", "Noto Sans SC", "Segoe UI", sans-serif;
  --mono: "JetBrains Mono", "Cascadia Code", Consolas, "Courier New", monospace;

  /* 间距 */
  --sp-section: clamp(56px, 8vw, 96px);
  --w-container: 1200px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--sans);
  color: var(--ink);
  background: var(--white);
  font-size: 15px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--blue-800); text-decoration: none; }
a:hover { color: var(--accent-dark); }

img, svg { display: block; max-width: 100%; }

.container { width: min(var(--w-container), 92%); margin: 0 auto; }

.mono { font-family: var(--mono); }

/* ---------- 顶部信息条 ---------- */
.topbar {
  background: var(--blue-950);
  color: #B9C6D4;
  font-size: 12.5px;
  border-bottom: 3px solid var(--accent);
}
.topbar-inner {
  display: flex; justify-content: space-between; align-items: center;
  height: 36px;
}
.topbar a { color: #D7E1EB; }
.topbar a:hover { color: var(--accent); }
.topbar .tb-item { display: inline-flex; align-items: center; gap: 6px; margin-right: 22px; }
.lang-switch { display: inline-flex; align-items: center; gap: 4px; }
.lang-switch .lang {
  padding: 2px 9px; border: 1px solid #33506E; color: #B9C6D4;
}
.lang-switch .lang.active { background: var(--accent); border-color: var(--accent); color: #fff; font-weight: 700; }
.lang-switch .lang.disabled { opacity: .45; cursor: not-allowed; }

/* ---------- 主导航 ---------- */
.site-header {
  background: var(--white);
  border-bottom: 1px solid var(--line);
  position: sticky; top: 0; z-index: 90;
  box-shadow: 0 1px 0 rgba(12,68,124,.04);
}
.header-inner { display: flex; align-items: center; gap: 40px; height: 76px; }

.brand { display: flex; align-items: center; gap: 14px; }
.brand-mark {
  width: 52px; height: 52px; background: var(--blue-800);
  display: grid; place-items: center; position: relative;
  color: #fff; font-weight: 900; font-size: 22px; letter-spacing: 1px;
}
.brand-mark::after {
  content: ""; position: absolute; right: -6px; bottom: -6px;
  width: 14px; height: 14px; background: var(--accent);
}
.brand-name { line-height: 1.2; }
.brand-name .cn { font-size: 18px; font-weight: 800; color: var(--blue-900); letter-spacing: 1.5px; text-transform: uppercase; }
.brand-name .en { font-size: 12px; color: var(--steel-400); letter-spacing: 1px; }

.main-nav { display: flex; gap: 6px; margin-left: auto; }
.main-nav a {
  padding: 8px 14px; font-size: 15px; font-weight: 600; color: var(--ink);
  border-bottom: 3px solid transparent;
}
.main-nav a:hover { color: var(--blue-800); background: var(--blue-050); }
.main-nav a.active { color: var(--blue-800); border-bottom-color: var(--accent); }

.header-search { display: flex; }
.header-search input {
  width: 200px; height: 38px; border: 1px solid var(--line); border-right: none;
  padding: 0 12px; font-size: 13px; outline: none; background: var(--bg);
}
.header-search input:focus { border-color: var(--blue-600); background: #fff; }
.header-search button {
  height: 38px; padding: 0 16px; border: none; background: var(--blue-800); color: #fff;
  font-size: 13px; cursor: pointer; font-family: var(--sans);
}
.header-search button:hover { background: var(--blue-600); }

.nav-toggle { display: none; }

/* ---------- 通用区块 ---------- */
.section { padding: var(--sp-section) 0; }
.section.tint { background: var(--bg); }
.section.dark { background: var(--blue-950); color: #D7E1EB; }

.sec-head { margin-bottom: 40px; }
.sec-kicker {
  display: inline-flex; align-items: center; gap: 10px;
  font-size: 13px; font-weight: 700; color: var(--accent-dark);
  letter-spacing: 3px; text-transform: uppercase; margin-bottom: 10px;
}
.sec-kicker::before { content: ""; width: 26px; height: 3px; background: var(--accent); }
.sec-title { font-size: clamp(24px, 3vw, 32px); font-weight: 800; color: var(--blue-900); letter-spacing: 1px; }
.sec-title .en { display: block; font-size: 13px; font-weight: 500; color: var(--steel-400); letter-spacing: 4px; margin-top: 4px; text-transform: uppercase; }
.sec-desc { color: var(--steel); max-width: 720px; margin-top: 12px; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px; justify-content: center;
  padding: 13px 30px; font-size: 15px; font-weight: 700; cursor: pointer;
  border: 2px solid transparent; font-family: var(--sans); transition: all .18s ease;
}
.btn-accent { background: var(--accent); color: #fff; }
.btn-accent:hover { background: var(--accent-dark); color: #fff; }
.btn-blue { background: var(--blue-800); color: #fff; }
.btn-blue:hover { background: var(--blue-600); color: #fff; }
.btn-outline { border-color: var(--blue-800); color: var(--blue-800); background: transparent; }
.btn-outline:hover { background: var(--blue-800); color: #fff; }
.btn-ghost-light { border-color: rgba(255,255,255,.5); color: #fff; }
.btn-ghost-light:hover { background: #fff; color: var(--blue-900); }
.btn-lg { padding: 16px 40px; font-size: 16px; }

/* ---------- 面包屑 ---------- */
.breadcrumb {
  background: var(--blue-050); border-bottom: 1px solid var(--line);
  font-size: 13px; color: var(--steel);
  padding: 14px 0;
}
.breadcrumb a { color: var(--steel); }
.breadcrumb a:hover { color: var(--blue-800); }
.breadcrumb .sep { margin: 0 8px; color: var(--steel-400); }
.breadcrumb .cur { color: var(--blue-800); font-weight: 600; }

/* ---------- 页面通栏标题 ---------- */
.page-hero {
  background:
    linear-gradient(115deg, rgba(10,46,82,.96) 0%, rgba(12,68,124,.92) 55%, rgba(21,90,156,.88) 100%),
    repeating-linear-gradient(0deg, transparent 0 39px, rgba(255,255,255,.05) 39px 40px),
    repeating-linear-gradient(90deg, transparent 0 39px, rgba(255,255,255,.05) 39px 40px);
  color: #fff; padding: 56px 0 52px;
  border-bottom: 4px solid var(--accent);
}
.page-hero h1 { font-size: clamp(26px, 3.4vw, 36px); font-weight: 800; letter-spacing: 1px; }
.page-hero .sub { color: #B9CCE0; margin-top: 8px; font-size: 15px; max-width: 760px; }

/* ============================================================
   首页 HERO
   ============================================================ */
.hero {
  background:
    linear-gradient(112deg, rgba(7,31,56,.97) 0%, rgba(12,68,124,.93) 58%, rgba(21,90,156,.85) 100%),
    repeating-linear-gradient(0deg, transparent 0 47px, rgba(255,255,255,.045) 47px 48px),
    repeating-linear-gradient(90deg, transparent 0 47px, rgba(255,255,255,.045) 47px 48px);
  color: #fff; padding: 88px 0 0; overflow: hidden;
}
.hero-grid { display: grid; grid-template-columns: 1.15fr .85fr; gap: 48px; align-items: center; padding-bottom: 72px; }
.hero-badge {
  display: inline-flex; align-items: center; gap: 8px;
  background: rgba(240,130,30,.14); border: 1px solid rgba(240,130,30,.55);
  color: #FFC07A; font-size: 13px; font-weight: 600; padding: 6px 14px; margin-bottom: 22px;
}
.hero h1 { font-size: clamp(30px, 4.4vw, 48px); line-height: 1.28; font-weight: 900; letter-spacing: 1px; }
.hero h1 em { font-style: normal; color: var(--accent); }
.hero .hero-sub { color: #B9CCE0; font-size: 16.5px; margin: 20px 0 34px; max-width: 560px; }
.hero-actions { display: flex; gap: 16px; flex-wrap: wrap; }
.hero-facts { display: flex; gap: 36px; margin-top: 44px; flex-wrap: wrap; }
.hero-facts .fact b { display: block; font-size: 26px; font-weight: 800; color: #fff; }
.hero-facts .fact b i { font-style: normal; color: var(--accent); }
.hero-facts .fact span { font-size: 12.5px; color: #8FA6BC; letter-spacing: 1px; }

.hero-visual { position: relative; }
.hero-visual .plate {
  background: rgba(255,255,255,.05); border: 1px solid rgba(255,255,255,.16);
  padding: 26px; position: relative;
}
.hero-visual .plate::before {
  content: "HD-A SERIES"; position: absolute; top: -11px; left: 18px;
  background: var(--accent); color: #fff; font-size: 11px; font-weight: 700;
  padding: 2px 10px; letter-spacing: 2px; font-family: var(--mono);
}
.hero-visual .plate figcaption { font-size: 12px; color: #8FA6BC; margin-top: 12px; font-family: var(--mono); }

/* 安全条纹 */
.hazard { height: 10px; background: repeating-linear-gradient(-45deg, var(--accent) 0 16px, var(--blue-950) 16px 32px); }

/* ---------- 数据条 ---------- */
.stats-band { background: var(--blue-950); color: #fff; }
.stats-band .row { display: grid; grid-template-columns: repeat(4, 1fr); }
.stats-band .cell { padding: 30px 20px; text-align: center; border-left: 1px solid rgba(255,255,255,.09); }
.stats-band .cell:first-child { border-left: none; }
.stats-band b { display: block; font-size: 30px; font-weight: 800; color: var(--accent); }
.stats-band span { font-size: 13px; color: #8FA6BC; letter-spacing: 1px; }

/* ---------- 两大板块入口 ---------- */
.duo-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; }
.duo-card {
  position: relative; background: var(--white); border: 1px solid var(--line);
  padding: 38px 36px 34px; transition: all .2s ease; overflow: hidden; display: block;
}
.duo-card:hover { border-color: var(--blue-600); box-shadow: 0 18px 40px -18px rgba(12,68,124,.35); transform: translateY(-3px); }
.duo-card::before { content: ""; position: absolute; top: 0; left: 0; width: 64px; height: 5px; background: var(--accent); }
.duo-card .tag {
  display: inline-block; font-size: 12px; font-weight: 700; letter-spacing: 2px;
  color: var(--steel); border: 1px solid var(--line); padding: 3px 10px; margin-bottom: 16px;
}
.duo-card h3 { font-size: 23px; font-weight: 800; color: var(--blue-900); margin-bottom: 12px; }
.duo-card p { color: var(--steel); font-size: 14px; margin-bottom: 20px; min-height: 66px; }
.duo-card .duo-foot { display: flex; align-items: center; justify-content: space-between; }
.duo-card .duo-foot .more { font-weight: 700; color: var(--blue-800); font-size: 14px; }
.duo-card .duo-foot .count { font-size: 12px; color: var(--steel-400); font-family: var(--mono); }
.duo-card .duo-img { margin: 18px 0 6px; }

/* ---------- 品牌墙 ---------- */
.brand-wall { display: grid; grid-template-columns: repeat(6, 1fr); gap: 14px; }
.brand-cell {
  background: var(--white); border: 1px solid var(--line);
  height: 92px; display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 3px; transition: all .18s ease;
}
.brand-cell:hover { border-color: var(--blue-600); }
.brand-cell b { font-size: 14px; color: var(--ink); font-weight: 800; letter-spacing: .5px; }
.brand-cell span { font-size: 11px; color: var(--steel-400); font-family: var(--mono); letter-spacing: 1px; }

/* ---------- 优势 ---------- */
.adv-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; }
.adv-card { background: var(--white); border: 1px solid var(--line); padding: 30px 26px; position: relative; }
.adv-card .num {
  font-family: var(--mono); font-size: 13px; font-weight: 700; color: var(--accent-dark);
  border-bottom: 2px solid var(--accent); padding-bottom: 6px; margin-bottom: 14px; display: inline-block;
}
.adv-card h4 { font-size: 17px; font-weight: 800; color: var(--blue-900); margin-bottom: 10px; }
.adv-card p { font-size: 13.5px; color: var(--steel); }

/* ---------- 产品卡片 ---------- */
.prod-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.prod-card { background: var(--white); border: 1px solid var(--line); transition: all .2s ease; display: flex; flex-direction: column; }
.prod-card:hover { border-color: var(--blue-600); box-shadow: 0 16px 36px -18px rgba(12,68,124,.3); }
.prod-card .thumb { background: var(--blue-050); border-bottom: 1px solid var(--line); padding: 18px; position: relative; }
.prod-card .thumb .badges { position: absolute; top: 10px; left: 10px; display: flex; gap: 6px; }
.badge {
  font-size: 11px; font-weight: 700; padding: 2px 8px; letter-spacing: .5px;
}
.badge.hd { background: var(--blue-800); color: #fff; }
.badge.oem { background: #fff; color: var(--accent-dark); border: 1px solid var(--accent); }
.badge.new { background: var(--accent); color: #fff; }
.prod-card .body { padding: 16px 18px 18px; display: flex; flex-direction: column; flex: 1; }
.prod-card .cat { font-size: 11.5px; color: var(--steel-400); letter-spacing: 1px; margin-bottom: 5px; }
.prod-card h4 { font-size: 15px; font-weight: 700; color: var(--ink); line-height: 1.45; }
.prod-card .pn { font-family: var(--mono); font-size: 12px; color: var(--blue-800); background: var(--blue-050); padding: 4px 8px; display: inline-block; margin: 10px 0; align-self: flex-start; }
.prod-card .oem-line { font-size: 12px; color: var(--steel); margin-bottom: 14px; }
.prod-card .oem-line b { color: var(--steel-400); font-weight: 600; }
.prod-card .go { margin-top: auto; font-size: 13px; font-weight: 700; color: var(--blue-800); }
.prod-card .go::after { content: " →"; }

/* ---------- CTA 横幅 ---------- */
.cta-band { background: var(--blue-800); color: #fff; padding: 52px 0; border-top: 4px solid var(--accent); }
.cta-band .row { display: flex; align-items: center; justify-content: space-between; gap: 32px; flex-wrap: wrap; }
.cta-band h3 { font-size: 24px; font-weight: 800; }
.cta-band p { color: #C4D5E6; margin-top: 6px; }

/* ---------- 询盘表单（联系页 / OEM页） ---------- */
.form-wrap { display: grid; grid-template-columns: 1fr 1.3fr; gap: 40px; align-items: start; }
.form-panel { background: var(--white); border: 1px solid var(--line); border-top: 4px solid var(--blue-800); padding: 34px 34px 28px; }
.form-panel h3 { font-size: 20px; font-weight: 800; color: var(--blue-900); margin-bottom: 6px; }
.form-panel .form-note { font-size: 13px; color: var(--steel); margin-bottom: 22px; }
.field-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.field { display: flex; flex-direction: column; gap: 6px; }
.field.full { grid-column: 1 / -1; }
.field label { font-size: 13px; font-weight: 700; color: var(--ink); }
.field label .req { color: #D64545; }
.field input, .field select, .field textarea {
  border: 1px solid var(--line); background: var(--bg);
  padding: 11px 13px; font-size: 14px; font-family: var(--sans); outline: none;
  transition: border-color .15s ease, background .15s ease;
}
.field input:focus, .field select:focus, .field textarea:focus { border-color: var(--blue-600); background: #fff; }
.field textarea { min-height: 110px; resize: vertical; }
.form-consent { display: flex; gap: 10px; align-items: flex-start; font-size: 12.5px; color: var(--steel); margin: 18px 0 20px; }
.form-consent input { margin-top: 4px; }
/* 蜜罐字段（反垃圾，视觉隐藏） */
.hp-field { position: absolute; left: -9999px; top: -9999px; }

.info-block { margin-bottom: 26px; }
.info-block h4 { font-size: 15px; font-weight: 800; color: var(--blue-900); margin-bottom: 8px; display: flex; align-items: center; gap: 8px; }
.info-block h4::before { content: ""; width: 8px; height: 8px; background: var(--accent); }
.info-block p, .info-block li { font-size: 14px; color: var(--steel); }
.info-block ul { list-style: none; }
.info-block li { padding: 3px 0; }

/* ---------- 列表页：筛选侧栏 ---------- */
.catalog-layout { display: grid; grid-template-columns: 264px 1fr; gap: 32px; align-items: start; }
.filter-panel { background: var(--white); border: 1px solid var(--line); position: sticky; top: 96px; }
.filter-panel .fp-head {
  background: var(--blue-900); color: #fff; font-size: 14px; font-weight: 700;
  padding: 12px 18px; letter-spacing: 1px;
}
.filter-group { padding: 16px 18px; border-bottom: 1px solid var(--line); }
.filter-group:last-child { border-bottom: none; }
.filter-group h5 { font-size: 13px; font-weight: 800; color: var(--ink); margin-bottom: 10px; letter-spacing: 1px; }
.f-opt { display: flex; align-items: center; gap: 9px; padding: 4px 0; font-size: 13.5px; color: var(--steel); cursor: pointer; }
.f-opt:hover { color: var(--blue-800); }
.f-opt input { accent-color: var(--blue-800); }
.f-opt .cnt { margin-left: auto; font-size: 11.5px; color: var(--steel-400); font-family: var(--mono); }

.catalog-toolbar {
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  background: var(--white); border: 1px solid var(--line); padding: 12px 18px; margin-bottom: 20px;
  font-size: 13.5px; color: var(--steel); flex-wrap: wrap;
}
.catalog-toolbar b { color: var(--blue-800); }
.chip-row { display: flex; gap: 8px; flex-wrap: wrap; }
.chip {
  font-size: 12px; font-family: var(--mono); background: var(--blue-050);
  border: 1px solid var(--line); color: var(--blue-800); padding: 3px 10px;
}
.chip.active { background: var(--blue-800); color: #fff; border-color: var(--blue-800); }

.cat-list { list-style: none; margin-bottom: 28px; }
.cat-list > li { border-bottom: 1px solid var(--line); }
.cat-list > li > a {
  display: flex; justify-content: space-between; align-items: center;
  padding: 13px 4px; font-size: 15px; font-weight: 700; color: var(--ink);
}
.cat-list > li > a:hover, .cat-list > li > a.cur { color: var(--blue-800); }
.cat-list > li > a .cnt { font-family: var(--mono); font-size: 12px; color: var(--steel-400); }
.cat-sub { list-style: none; padding: 0 4px 12px 18px; }
.cat-sub li a { display: flex; justify-content: space-between; padding: 5px 0; font-size: 13.5px; color: var(--steel); }
.cat-sub li a:hover, .cat-sub li a.cur { color: var(--accent-dark); font-weight: 600; }
.cat-sub .cnt { font-family: var(--mono); font-size: 11.5px; color: var(--steel-400); }

.pagination { display: flex; gap: 8px; justify-content: center; margin-top: 36px; }
.pagination a, .pagination span {
  min-width: 40px; height: 40px; display: grid; place-items: center;
  border: 1px solid var(--line); font-size: 14px; color: var(--steel); background: #fff;
}
.pagination .cur { background: var(--blue-800); color: #fff; border-color: var(--blue-800); font-weight: 700; }
.pagination a:hover { border-color: var(--blue-600); color: var(--blue-800); }

/* ---------- 产品详情 ---------- */
.pd-layout { display: grid; grid-template-columns: 1fr 1fr; gap: 44px; align-items: start; margin-bottom: 52px; }
.pd-gallery .main { background: var(--blue-050); border: 1px solid var(--line); padding: 30px; }
.pd-gallery .thumbs { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; margin-top: 10px; }
.pd-gallery .thumbs button {
  background: var(--blue-050); border: 1px solid var(--line); padding: 8px; cursor: pointer;
}
.pd-gallery .thumbs button:hover, .pd-gallery .thumbs button.cur { border-color: var(--accent); }
.pd-info .cat-line { font-size: 13px; color: var(--steel-400); letter-spacing: 1px; margin-bottom: 6px; }
.pd-info h1 { font-size: 26px; font-weight: 800; color: var(--blue-900); line-height: 1.4; }
.pd-info .pn-row { display: flex; gap: 10px; align-items: center; margin: 14px 0 18px; flex-wrap: wrap; }
.pd-info .pn-row .pn-label { font-size: 13px; color: var(--steel); font-weight: 600; }
.pd-info .pn { font-family: var(--mono); font-size: 15px; font-weight: 700; color: var(--blue-800); background: var(--blue-050); border: 1px solid var(--blue-100); padding: 5px 12px; }
.pd-oem { background: var(--white); border: 1px dashed var(--blue-600); padding: 18px 20px; margin-bottom: 22px; }
.pd-oem h5 { font-size: 13.5px; font-weight: 800; color: var(--blue-900); margin-bottom: 10px; letter-spacing: 1px; }
.pd-oem .oem-chips { display: flex; flex-wrap: wrap; gap: 8px; }
.oem-chip {
  font-family: var(--mono); font-size: 13px; padding: 5px 12px;
  background: var(--bg); border: 1px solid var(--line); color: var(--ink);
}
.oem-chip b { color: var(--steel-400); font-weight: 600; margin-right: 6px; font-size: 11.5px; }
.pd-actions { display: flex; gap: 14px; margin-top: 26px; flex-wrap: wrap; }
.pd-note { font-size: 12.5px; color: var(--steel-400); margin-top: 16px; }

.spec-table { width: 100%; border-collapse: collapse; font-size: 14px; }
.spec-table caption { text-align: left; font-weight: 800; font-size: 18px; color: var(--blue-900); padding-bottom: 14px; letter-spacing: 1px; }
.spec-table th, .spec-table td { border: 1px solid var(--line); padding: 11px 16px; text-align: left; vertical-align: top; }
.spec-table th { background: var(--blue-050); color: var(--blue-900); font-weight: 700; width: 220px; }
.spec-table td { color: var(--ink); }
.spec-table tr:nth-child(even) td { background: #FAFBFC; }

.pd-section { margin-top: 46px; }
.pd-section h2 {
  font-size: 20px; font-weight: 800; color: var(--blue-900); margin-bottom: 18px;
  padding-left: 14px; border-left: 5px solid var(--accent); letter-spacing: 1px;
}
.pd-section p { color: var(--steel); margin-bottom: 12px; }

/* ---------- 下载资料 ---------- */
.dl-list { display: flex; flex-direction: column; gap: 14px; }
.dl-item {
  display: flex; align-items: center; gap: 22px; background: var(--white);
  border: 1px solid var(--line); padding: 22px 26px; transition: border-color .18s ease;
}
.dl-item:hover { border-color: var(--blue-600); }
.dl-icon { width: 52px; height: 60px; flex: none; }
.dl-meta { flex: 1; }
.dl-meta h4 { font-size: 16px; font-weight: 700; color: var(--ink); }
.dl-meta p { font-size: 13px; color: var(--steel); margin-top: 3px; }
.dl-meta .dl-tags { display: flex; gap: 8px; margin-top: 8px; flex-wrap: wrap; }
.dl-meta .dl-tags span { font-size: 11.5px; font-family: var(--mono); color: var(--steel-400); border: 1px solid var(--line); padding: 2px 8px; }

/* ---------- 关于页 ---------- */
.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 44px; align-items: center; }
.about-copy h3 { font-size: 20px; font-weight: 800; color: var(--blue-900); margin: 22px 0 10px; }
.about-copy h3:first-child { margin-top: 0; }
.about-copy p { color: var(--steel); margin-bottom: 12px; }
.timeline { border-left: 3px solid var(--blue-100); margin-left: 8px; padding-left: 26px; }
.timeline .tl-item { position: relative; padding-bottom: 26px; }
.timeline .tl-item::before {
  content: ""; position: absolute; left: -33px; top: 6px; width: 12px; height: 12px;
  background: var(--accent); border: 3px solid var(--blue-050);
}
.timeline .tl-item b { display: block; font-family: var(--mono); font-size: 14px; color: var(--blue-800); }
.timeline .tl-item h4 { font-size: 15px; font-weight: 700; color: var(--ink); margin: 2px 0; }
.timeline .tl-item p { font-size: 13.5px; color: var(--steel); }

/* ---------- OEM 页流程 ---------- */
.steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: 0; counter-reset: step; }
.step { padding: 26px 24px 26px 0; position: relative; counter-increment: step; }
.step::before {
  content: "0" counter(step); font-family: var(--mono); font-size: 40px; font-weight: 800;
  color: var(--blue-100); display: block; line-height: 1; margin-bottom: 12px;
}
.step h4 { font-size: 16px; font-weight: 800; color: var(--blue-900); margin-bottom: 8px; }
.step p { font-size: 13.5px; color: var(--steel); }
.step:not(:last-child)::after {
  content: ""; position: absolute; right: 0; top: 30px; bottom: 30px; width: 1px; background: var(--line);
}

.cap-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.cap-card { background: var(--white); border: 1px solid var(--line); padding: 26px; }
.cap-card h4 { font-size: 16px; font-weight: 800; color: var(--blue-900); margin-bottom: 8px; }
.cap-card p { font-size: 13.5px; color: var(--steel); }

/* ---------- 页脚 ---------- */
.site-footer { background: var(--blue-950); color: #9DB0C2; font-size: 13.5px; }
.footer-main { display: grid; grid-template-columns: 1.5fr 1fr 1fr 1.2fr; gap: 40px; padding: 56px 0 40px; }
.footer-main h5 { color: #fff; font-size: 14px; font-weight: 800; letter-spacing: 2px; margin-bottom: 16px; }
.footer-main ul { list-style: none; }
.footer-main li { padding: 4px 0; }
.footer-main a { color: #9DB0C2; }
.footer-main a:hover { color: var(--accent); }
.footer-brand .brand-mark { margin-bottom: 14px; }
.footer-brand p { line-height: 1.8; }
.footer-contact li { display: flex; gap: 10px; align-items: baseline; }
.footer-contact li b { color: #C4D5E6; font-weight: 600; flex: none; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,.09); padding: 18px 0;
  display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; font-size: 12.5px;
}
.footer-bottom .proto-note { color: #64788C; }
.footer-bottom .note { color: #64788C; }

/* ---------- 响应式 ---------- */
@media (max-width: 1080px) {
  .main-nav { display: none; }
  .nav-toggle { display: grid; place-items: center; margin-left: auto; width: 44px; height: 44px; border: 1px solid var(--line); background: none; cursor: pointer; }
  .nav-toggle span { display: block; width: 20px; height: 2px; background: var(--ink); margin: 2.5px 0; }
  .main-nav.open { display: flex; flex-direction: column; position: absolute; top: 76px; left: 0; right: 0; background: #fff; border-bottom: 1px solid var(--line); padding: 10px 4%; }
  .header-search { display: none; }
  .hero-grid { grid-template-columns: 1fr; }
  .duo-grid, .adv-grid, .cap-grid { grid-template-columns: 1fr 1fr; }
  .prod-grid { grid-template-columns: repeat(3, 1fr); }
  .brand-wall { grid-template-columns: repeat(3, 1fr); }
  .stats-band .row { grid-template-columns: 1fr 1fr; }
  .catalog-layout { grid-template-columns: 1fr; }
  .filter-panel { position: static; }
  .pd-layout, .form-wrap, .about-grid { grid-template-columns: 1fr; }
  .steps { grid-template-columns: 1fr 1fr; }
  .step:not(:last-child)::after { display: none; }
  .footer-main { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 640px) {
  .duo-grid, .adv-grid, .prod-grid, .cap-grid, .steps, .field-grid { grid-template-columns: 1fr; }
  .brand-wall { grid-template-columns: repeat(2, 1fr); }
  .topbar-inner { justify-content: center; }
  .topbar .tb-mail { display: none; }
}

/* ============================================================
   红色导航变体（产品中心2 / 机械配件 / 滤清器 页面）
   ============================================================ */
.site-header.red-nav {
  background: #C41E1A;
  border-bottom: 1px solid #8B0000;
  box-shadow: 0 2px 8px rgba(196,30,26,.18);
}
.site-header.red-nav .brand-name .cn { color: #fff; }
.site-header.red-nav .brand-name .en { color: rgba(255,255,255,.65); }
.site-header.red-nav .brand-mark { background: #fff; color: #C41E1A; }
.site-header.red-nav .brand-mark::after { background: #FFD700; }
.site-header.red-nav .main-nav a { color: #fff; }
.site-header.red-nav .main-nav a:hover { color: #FFD700; background: rgba(255,255,255,.12); }
.site-header.red-nav .main-nav a.active { color: #FFD700; border-bottom-color: #FFD700; }
.site-header.red-nav .nav-toggle { border-color: rgba(255,255,255,.4); }
.site-header.red-nav .nav-toggle span { background: #fff; }
.site-header.red-nav .header-search input { background: rgba(255,255,255,.15); border-color: rgba(255,255,255,.3); color: #fff; }
.site-header.red-nav .header-search input::placeholder { color: rgba(255,255,255,.5); }
.site-header.red-nav .header-search button { background: #8B0000; }
.site-header.red-nav .header-search button:hover { background: #6B0000; }
.site-header.red-nav .main-nav.open { background: #C41E1A; }

/* ---------- 全量导航（9 项时隐藏搜索框，紧凑布局） ---------- */
.site-header.full-nav .header-search { display: none; }
.main-nav a { padding: 8px 11px; font-size: 14px; }