/* =============================================================================
 * HBY — main.css
 * 设计方向：Premium / Technical / Minimal / Automotive / Dark / GCC
 * 单文件 CSS，无预处理器、无外部依赖（字体走系统字体栈，加载 0 请求）
 * ==========================================================================
 * 目录
 *   01 设计变量 (Design tokens)
 *   02 基础重置 (Reset & base)
 *   03 排版与工具类 (Typography / helpers)
 *   04 按钮 (Buttons)
 *   05 站点头部与导航 (Header / Nav)
 *   06 Hero
 *   07 卖点 (Benefits)
 *   08 产品 (Products / Specs)
 *   09 B2B / OEM / 流程 (Trade / OEM / Process)
 *   10 FAQ
 *   11 询价表单 (Quote)
 *   12 页脚 (Footer)
 *   13 响应式 (Media queries)
 *   14 无障碍与动效偏好
 * ========================================================================== */

/* ============================================================ 01 设计变量 */
:root {
  /* 背景与表面 */
  --bg:            #07080a;
  --bg-alt:        #0b0d11;
  --surface:       #111418;
  --surface-2:     #161a20;
  --surface-3:     #1c2128;

  /* 描边 */
  --line:          rgba(255, 255, 255, .08);
  --line-mid:      rgba(255, 255, 255, .13);
  --line-strong:   rgba(255, 255, 255, .22);

  /* 文本 */
  --text:          #f3f5f7;
  --text-soft:     #c3cad3;
  --muted:         #949daa;
  --muted-2:       #6d7684;

  /* 强调色（暖金 — 太阳 / 隔热 / GCC 高端感） */
  --accent:        #e3a850;
  --accent-bright: #f2bf6c;
  --accent-deep:   #b8792a;
  --accent-soft:   rgba(227, 168, 80, .12);
  --accent-line:   rgba(227, 168, 80, .32);

  /* 玻璃类产品色（用于产品卡色片，仅作视觉示意） */
  --shade-15: #14161a;
  --shade-35: #26292f;
  --shade-45: #343840;

  /* 尺寸与节奏 */
  --container:     1200px;
  --radius-sm:     6px;
  --radius:        12px;
  --radius-lg:     18px;
  --section-y:     clamp(64px, 8vw, 116px);

  /* 字体 */
  --font-sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue",
               Arial, "Noto Sans", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
               "Liberation Mono", monospace;

  /* 阴影 */
  --shadow:    0 18px 48px rgba(0, 0, 0, .45);
  --shadow-sm: 0 8px 22px rgba(0, 0, 0, .35);
}

/* ========================================================= 02 基础重置 */
*, *::before, *::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: 88px;          /* 锚点跳转避开固定导航 */
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

body.nav-open { overflow: hidden; }

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

a { color: inherit; text-decoration: none; }
a:hover { color: var(--accent-bright); }

button, input, select, textarea { font: inherit; color: inherit; }

hr { border: 0; border-top: 1px solid var(--line); margin: 0; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

::selection { background: var(--accent); color: #10120f; }

/* ================================================ 03 排版与工具类 */
h1, h2, h3, h4 {
  margin: 0;
  font-weight: 650;
  line-height: 1.12;
  letter-spacing: -.02em;
  color: var(--text);
}

h1 { font-size: clamp(2rem, 4.2vw, 3.1rem); }
h2 { font-size: clamp(1.7rem, 3.4vw, 2.5rem); }
h3 { font-size: clamp(1.12rem, 1.6vw, 1.3rem); }
h4 { font-size: 1rem; letter-spacing: -.01em; }

p  { margin: 0 0 1rem; color: var(--text-soft); }
p:last-child { margin-bottom: 0; }

.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: clamp(20px, 4vw, 40px);
}

.section { padding-block: var(--section-y); position: relative; }
.section--alt { background: var(--bg-alt); border-block: 1px solid var(--line); }

/* 区块标题组 */
.section-head { max-width: 720px; margin-bottom: clamp(32px, 4vw, 56px); }
.section-head--center { margin-inline: auto; text-align: center; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 16px;
  font-size: .72rem;
  font-weight: 600;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--accent);
}
.eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  background: var(--accent-line);
}

.lead {
  font-size: clamp(1rem, 1.4vw, 1.08rem);
  color: var(--muted);
  line-height: 1.7;
}
/* 与上一个 .lead 之间留一段间距（替代行内 style，便于上 CSP） */
.lead--spaced { margin-top: 16px; }

.mono { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }
.text-accent { color: var(--accent); }
.visually-hidden {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

/* 细网格背景（技术感，纯 CSS，无图片请求） */
.grid-bg::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,.028) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.028) 1px, transparent 1px);
  background-size: 64px 64px;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 0%, #000 25%, transparent 78%);
  -webkit-mask-image: radial-gradient(ellipse 80% 60% at 50% 0%, #000 25%, transparent 78%);
  pointer-events: none;
}

/* ============================================================ 04 按钮 */
.btn {
  --btn-bg: transparent;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 13px 22px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  background: var(--btn-bg);
  color: var(--text);
  font-size: .92rem;
  font-weight: 600;
  letter-spacing: .01em;
  cursor: pointer;
  white-space: nowrap;
  transition: background-color .18s ease, border-color .18s ease,
              color .18s ease, transform .18s ease;
}
.btn:hover { transform: translateY(-1px); }
.btn svg { width: 17px; height: 17px; flex: none; }

.btn--primary {
  background: linear-gradient(180deg, var(--accent-bright), var(--accent));
  border-color: transparent;
  color: #191307;
  box-shadow: 0 10px 26px rgba(227, 168, 80, .18);
}
.btn--primary:hover {
  background: linear-gradient(180deg, #f7c982, var(--accent-bright));
  color: #191307;
}

.btn--ghost { background: rgba(255,255,255,.03); }
.btn--ghost:hover {
  background: rgba(255,255,255,.07);
  border-color: var(--line-strong);
  color: var(--text);
}

.btn--wa {
  background: rgba(37, 211, 102, .1);
  border-color: rgba(37, 211, 102, .35);
  color: #d6ffe6;
}
.btn--wa:hover { background: rgba(37, 211, 102, .18); color: #eafff2; }

.btn--sm { padding: 10px 16px; font-size: .85rem; }
.btn--block { width: 100%; }

/* ================================================ 05 头部与导航 */
.skip-link {
  position: absolute; left: 16px; top: -60px; z-index: 100;
  padding: 10px 16px; border-radius: var(--radius-sm);
  background: var(--accent); color: #191307; font-weight: 600;
  transition: top .2s ease;
}
.skip-link:focus { top: 14px; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: rgba(7, 8, 10, .72);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color .2s ease, background-color .2s ease;
}
.site-header.is-scrolled {
  border-bottom-color: var(--line);
  background: rgba(7, 8, 10, .92);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 68px;
}

/* 品牌标 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  font-weight: 700;
  letter-spacing: .13em;
  font-size: .95rem;
  text-transform: uppercase;
}
.brand:hover { color: var(--text); }
.brand__mark {
  width: 32px; height: 32px; flex: none;
  display: grid; place-items: center;
  border: 1px solid var(--accent-line);
  border-radius: 8px;
  background: linear-gradient(145deg, rgba(227,168,80,.2), rgba(227,168,80,.03));
  font-family: var(--font-mono);
  font-size: .95rem;
  color: var(--accent-bright);
  letter-spacing: 0;
}

.nav__links {
  display: flex;
  align-items: center;
  gap: 4px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.nav__links a {
  display: block;
  padding: 9px 13px;
  border-radius: var(--radius-sm);
  font-size: .89rem;
  font-weight: 500;
  color: var(--text-soft);
  transition: color .16s ease, background-color .16s ease;
}
.nav__links a:hover { color: var(--text); background: rgba(255,255,255,.05); }
.nav__links a.is-active { color: var(--accent); }

.nav__actions { display: flex; align-items: center; gap: 10px; }

.nav__toggle {
  display: none;
  width: 42px; height: 42px;
  border: 1px solid var(--line-mid);
  border-radius: var(--radius-sm);
  background: rgba(255,255,255,.03);
  cursor: pointer;
}
.nav__toggle span {
  display: block;
  width: 18px; height: 1.5px;
  margin: 4px auto;
  background: var(--text);
  transition: transform .2s ease, opacity .2s ease;
}
.nav__toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(5.5px) rotate(45deg); }
.nav__toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav__toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-5.5px) rotate(-45deg); }

/* =============================================================== 06 Hero */
.hero {
  position: relative;
  overflow: hidden;
  padding-block: clamp(56px, 7vw, 96px) clamp(64px, 8vw, 108px);
  border-bottom: 1px solid var(--line);
}
.hero::after {                       /* 斜向阳光光斑 */
  content: "";
  position: absolute;
  top: -30%; right: -12%;
  width: 62vw; height: 62vw;
  max-width: 900px; max-height: 900px;
  background:
    radial-gradient(circle at 50% 50%, rgba(227,168,80,.16), transparent 62%),
    radial-gradient(circle at 30% 70%, rgba(120,150,255,.07), transparent 60%);
  filter: blur(8px);
  pointer-events: none;
}

.hero__inner {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
  gap: clamp(32px, 5vw, 68px);
  align-items: center;
}

.hero h1 { margin-bottom: 20px; }
.hero h1 .accent-line { display: block; color: var(--accent); }

.hero__sub {
  max-width: 46ch;
  font-size: clamp(1rem, 1.35vw, 1.1rem);
  color: var(--muted);
}

.hero__cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

/* Hero 供应方式一行（B2B 信息） */
.hero__supply {
  margin-top: 20px;
  font-size: .82rem;
  letter-spacing: .04em;
  color: var(--muted-2);
}

/* Hero 下方信任条 */
.hero__facts {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  margin: clamp(36px, 5vw, 60px) 0 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}
.hero__facts li {
  padding: 18px 20px;
  background: rgba(255,255,255,.014);
}
.hero__facts dt,
.hero__facts .fact__k {
  display: block;
  font-size: .68rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--muted-2);
}
.hero__facts .fact__v {
  display: block;
  margin-top: 5px;
  font-size: .98rem;
  font-weight: 600;
  color: var(--text);
}

/* Hero 视觉 */
.hero__visual {
  position: relative;
  border: 1px solid var(--line-mid);
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: #0a0c10;
  box-shadow: var(--shadow);
}
.hero__visual img,
.hero__visual svg { width: 100%; height: auto; display: block; }
.hero__visual figcaption {
  position: absolute;
  left: 14px; bottom: 12px;
  padding: 6px 11px;
  border: 1px solid var(--line-mid);
  border-radius: 100px;
  background: rgba(7,8,10,.7);
  backdrop-filter: blur(6px);
  font-size: .7rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--muted);
}

/* ====================================================== 07 卖点 Benefits */
.grid { display: grid; gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }

.benefit {
  padding: clamp(24px, 2.6vw, 34px);
  background: var(--surface);
  transition: background-color .2s ease;
}
.benefit:hover { background: var(--surface-2); }

.benefit__icon {
  width: 40px; height: 40px;
  margin-bottom: 18px;
  display: grid; place-items: center;
  border: 1px solid var(--accent-line);
  border-radius: 10px;
  background: var(--accent-soft);
  color: var(--accent-bright);
}
.benefit__icon svg { width: 20px; height: 20px; }

.benefit h3 { margin-bottom: 9px; }
.benefit p { font-size: .92rem; color: var(--muted); }
.benefit__note {
  display: block;
  margin-top: 14px;
  padding-top: 13px;
  border-top: 1px dashed var(--line);
  font-size: .76rem;
  letter-spacing: .04em;
  color: var(--muted-2);
}

/* ======================================================== 08 产品 Products */
.product-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(16px, 2vw, 24px);
}

.product {
  position: relative;
  display: flex;
  flex-direction: column;
  border: 1px solid var(--line-mid);
  border-radius: var(--radius-lg);
  background: linear-gradient(180deg, var(--surface-2), var(--surface));
  overflow: hidden;
  transition: border-color .2s ease, transform .2s ease;
}
.product:hover { border-color: var(--accent-line); transform: translateY(-3px); }

.product--featured { border-color: var(--accent-line); }
.product--featured::before {
  content: "";
  position: absolute; inset: 0 0 auto 0; height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
}

.product__badge {
  position: absolute;
  top: 14px; right: 14px;
  z-index: 2;
  padding: 5px 11px;
  border-radius: 100px;
  background: var(--accent);
  color: #191307;
  font-size: .68rem;
  font-weight: 700;
  letter-spacing: .12em;
  text-transform: uppercase;
}

/* 产品视觉：抽象膜面色片（不是伪造的产品包装照片） */
.product__media {
  position: relative;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  border-bottom: 1px solid var(--line);
  background: #0a0c10;
}
.product__media img { width: 100%; height: 100%; object-fit: cover; }
.product__media-note {
  position: absolute;
  top: 12px; left: 12px;
  padding: 4px 10px;
  border: 1px solid var(--line-mid);
  border-radius: 100px;
  background: rgba(7, 8, 10, .74);
  -webkit-backdrop-filter: blur(4px);
  backdrop-filter: blur(4px);
  font-size: .64rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--text-soft);
}

.product__body { padding: clamp(20px, 2.2vw, 26px); display: flex; flex-direction: column; flex: 1; }

.product__name {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin-bottom: 4px;
}
.product__name strong { font-size: 1.35rem; font-weight: 700; letter-spacing: .02em; }
.product__series { font-size: .74rem; letter-spacing: .14em; text-transform: uppercase; color: var(--muted-2); }

.product__vlt {
  display: flex;
  align-items: flex-end;
  gap: 8px;
  margin: 12px 0 4px;
}
.product__vlt b {
  font-family: var(--font-mono);
  font-size: 2.15rem;
  font-weight: 600;
  line-height: 1;
  color: var(--text);
}
.product__vlt span { font-size: .74rem; letter-spacing: .1em; color: var(--muted-2); padding-bottom: 4px; }

.product__position { margin: 14px 0 0; font-size: .93rem; color: var(--muted); }

/* 快速事实行 */
.product__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
}
.product__facts li {
  padding: 5px 10px;
  border: 1px solid var(--line);
  border-radius: 100px;
  font-size: .75rem;
  color: var(--text-soft);
}

.product__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: auto;
  padding-top: 22px;
}

/* Technical Specs 折叠面板（原生 details，无 JS 依赖、无 console error） */
.specs {
  margin-top: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(0,0,0,.22);
  overflow: hidden;
}
.specs > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 14px;
  font-size: .84rem;
  font-weight: 600;
  color: var(--text-soft);
  cursor: pointer;
  list-style: none;
}
.specs > summary::-webkit-details-marker { display: none; }
.specs > summary:hover { background: rgba(255,255,255,.035); color: var(--text); }
.specs > summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--accent);
  transition: transform .2s ease;
}
.specs[open] > summary::after { content: "−"; }
.specs[open] > summary { border-bottom: 1px solid var(--line); }

.specs__table { width: 100%; border-collapse: collapse; font-size: .83rem; }
.specs__table caption {
  padding: 12px 14px 0;
  text-align: left;
  font-size: .72rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--muted-2);
}
.specs__table th,
.specs__table td {
  padding: 9px 14px;
  text-align: left;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}
.specs__table tr:last-child th,
.specs__table tr:last-child td { border-bottom: 0; }
.specs__table th { font-weight: 500; color: var(--muted); width: 58%; }
.specs__table td { font-family: var(--font-mono); color: var(--text); }
.specs__table td.is-pending { font-family: var(--font-sans); font-style: italic; color: var(--muted-2); }
.specs__note {
  margin: 0;
  padding: 12px 14px;
  border-top: 1px solid var(--line);
  font-size: .74rem;
  line-height: 1.55;
  color: var(--muted-2);
  background: rgba(0,0,0,.2);
}

/* 产品对比总表 */
.compare { margin-top: clamp(28px, 3vw, 44px); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.compare table { width: 100%; border-collapse: collapse; font-size: .88rem; }
.compare th, .compare td { padding: 14px 16px; text-align: left; border-bottom: 1px solid var(--line); }
.compare thead th {
  background: var(--surface-2);
  font-size: .72rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 600;
}
.compare tbody th { font-weight: 500; color: var(--text-soft); }
.compare td { font-family: var(--font-mono); color: var(--text); }
.compare td.is-pending { font-family: var(--font-sans); font-style: italic; color: var(--muted-2); }
.compare tr:last-child th, .compare tr:last-child td { border-bottom: 0; }
.compare .col-featured { background: rgba(227,168,80,.06); }

.data-note {
  display: flex;
  gap: 12px;
  margin-top: 18px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-left: 2px solid var(--accent-line);
  border-radius: var(--radius-sm);
  background: rgba(255,255,255,.02);
  font-size: .82rem;
  color: var(--muted);
}
.data-note svg { width: 16px; height: 16px; flex: none; margin-top: 3px; color: var(--accent); }

/* ============================================ 09 B2B / OEM / 流程 */
.two-col {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: clamp(32px, 5vw, 72px);
  align-items: center;
}

.trade-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}
.trade-list li {
  padding: 20px 22px;
  background: var(--surface);
  font-size: .92rem;
  font-weight: 600;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 11px;
}
.trade-list li::before {
  content: "";
  width: 6px; height: 6px; flex: none;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

/* OEM 区块 */
.oem {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--accent-line);
  border-radius: var(--radius-lg);
  background:
    radial-gradient(ellipse 70% 100% at 100% 0%, rgba(227,168,80,.13), transparent 65%),
    linear-gradient(180deg, var(--surface-2), var(--surface));
  padding: clamp(28px, 4vw, 56px);
}
.oem__inner { position: relative; z-index: 1; max-width: 640px; }
/* OEM 卡片跟在 Trade 列表下方时留出间距（替代行内 style） */
.oem--stacked { margin-top: 24px; }
.oem blockquote {
  margin: 22px 0 26px;
  padding-left: 18px;
  border-left: 2px solid var(--accent-line);
  font-size: 1.02rem;
  line-height: 1.7;
  color: var(--text-soft);
}

/* 流程 */
.steps {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  counter-reset: step;
}
.steps li {
  position: relative;
  padding: clamp(22px, 2.6vw, 32px);
  background: var(--surface);
}
.steps .step__num {
  font-family: var(--font-mono);
  font-size: .8rem;
  letter-spacing: .12em;
  color: var(--accent);
}
.steps h3 { margin: 14px 0 8px; font-size: 1.05rem; }
.steps p { font-size: .88rem; color: var(--muted); }

.steps-cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px 22px;
  margin-top: 26px;
  padding: 18px 22px;
  border: 1px solid var(--line-mid);
  border-radius: var(--radius);
  background: rgba(255,255,255,.02);
}
.steps-cta strong {
  font-size: 1.02rem;
  letter-spacing: .01em;
}
.steps-cta .arrow { color: var(--accent); font-family: var(--font-mono); }
.steps-cta__note { font-size: .9rem; color: var(--muted); }

/* ============================================================ 10 FAQ */
.faq { max-width: 900px; margin-inline: auto; }
.faq__item {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  margin-bottom: 10px;
  overflow: hidden;
}
.faq__item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 20px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
}
.faq__item summary::-webkit-details-marker { display: none; }
.faq__item summary:hover { color: var(--accent-bright); }
.faq__item summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 1.1rem;
  color: var(--accent);
  flex: none;
}
.faq__item[open] summary::after { content: "−"; }
.faq__item[open] summary { border-bottom: 1px solid var(--line); }
.faq__a { padding: 16px 20px 20px; margin: 0; font-size: .93rem; color: var(--muted); }

/* ======================================================= 11 询价表单 */
.quote-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.45fr) minmax(0, .85fr);
  gap: clamp(24px, 3vw, 40px);
  align-items: start;
}

.form-card {
  border: 1px solid var(--line-mid);
  border-radius: var(--radius-lg);
  background: linear-gradient(180deg, var(--surface-2), var(--surface));
  padding: clamp(22px, 3vw, 36px);
  box-shadow: var(--shadow-sm);
}

.form-row { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
.field { margin-bottom: 16px; }
.field--full { grid-column: 1 / -1; }

.field label {
  display: block;
  margin-bottom: 7px;
  font-size: .8rem;
  font-weight: 600;
  letter-spacing: .04em;
  color: var(--text-soft);
}
.field .req { color: var(--accent); margin-left: 3px; }
.field .hint { display: block; margin-top: 6px; font-size: .74rem; color: var(--muted-2); }

.field input,
.field select,
.field textarea {
  width: 100%;
  padding: 12px 14px;
  border: 1px solid var(--line-mid);
  border-radius: var(--radius-sm);
  background: rgba(0,0,0,.28);
  color: var(--text);
  font-size: .92rem;
  transition: border-color .16s ease, background-color .16s ease;
}
.field input::placeholder,
.field textarea::placeholder { color: var(--muted-2); }
.field input:focus,
.field select:focus,
.field textarea:focus {
  outline: none;
  border-color: var(--accent);
  background: rgba(0,0,0,.4);
}
.field textarea { min-height: 118px; resize: vertical; }

.field select {
  appearance: none;
  -webkit-appearance: none;
  background-image: linear-gradient(45deg, transparent 50%, var(--muted) 50%),
                    linear-gradient(135deg, var(--muted) 50%, transparent 50%);
  background-position: calc(100% - 19px) calc(50% + 1px), calc(100% - 14px) calc(50% + 1px);
  background-size: 5px 5px, 5px 5px;
  background-repeat: no-repeat;
  padding-right: 38px;
}
.field select option { background: var(--surface-2); color: var(--text); }

.form-foot {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
  margin-top: 6px;
}
.form-foot .small { font-size: .78rem; color: var(--muted-2); }

.form-status {
  margin: 14px 0 0;
  padding: 0;
  font-size: .84rem;
  min-height: 0;
}
.form-status[data-state] {
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--line-mid);
  background: rgba(255,255,255,.03);
}
.form-status[data-state="success"] { border-color: rgba(37,211,102,.4); color: #c9f7d9; background: rgba(37,211,102,.08); }
.form-status[data-state="error"]   { border-color: rgba(255,120,120,.4); color: #ffd2d2; background: rgba(255,120,120,.08); }

/* 右侧直达联系方式 */
.contact-card {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  padding: clamp(20px, 2.4vw, 28px);
  position: sticky;
  top: 92px;
}
.contact-card h3 { margin-bottom: 6px; }
.contact-card > p { font-size: .86rem; color: var(--muted); margin-bottom: 20px; }

.contact-list { list-style: none; margin: 0 0 20px; padding: 0; display: grid; gap: 10px; }
.contact-list a,
.contact-list .contact-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: rgba(255,255,255,.02);
  font-size: .88rem;
  color: var(--text-soft);
  transition: border-color .16s ease, background-color .16s ease;
}
.contact-list a:hover { border-color: var(--accent-line); background: rgba(227,168,80,.06); color: var(--text); }
.contact-list svg { width: 17px; height: 17px; flex: none; color: var(--accent); }
.contact-list .contact-item { cursor: default; }

.contact-meta { margin: 0; padding-top: 18px; border-top: 1px solid var(--line); font-size: .78rem; color: var(--muted-2); }
.contact-meta strong { color: var(--text-soft); font-weight: 600; }

/* ========================================================== 12 页脚 */
.site-footer {
  border-top: 1px solid var(--line);
  background: var(--bg-alt);
  padding-block: clamp(40px, 5vw, 64px) 28px;
}
.footer__top {
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) repeat(2, minmax(0, .8fr));
  gap: clamp(24px, 4vw, 56px);
  padding-bottom: 32px;
  border-bottom: 1px solid var(--line);
}
.footer__brand p { margin-top: 14px; max-width: 40ch; font-size: .86rem; color: var(--muted); }
.footer__brand .footer__note { margin-top: 12px; }
.footer__col h4 {
  font-size: .72rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--muted-2);
  margin-bottom: 14px;
}
.footer__col ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 9px; }
.footer__col a { font-size: .87rem; color: var(--text-soft); }
.footer__col a:hover { color: var(--accent-bright); }

.footer__bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 12px;
  padding-top: 22px;
  font-size: .76rem;
  color: var(--muted-2);
}
.footer__legal { max-width: 78ch; }

/* ===================================================== 13 响应式 */
@media (max-width: 1024px) {
  .hero__inner { grid-template-columns: 1fr; }
  .hero__visual { order: -1; max-width: 620px; }
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .product-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .steps { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .quote-grid { grid-template-columns: 1fr; }
  .contact-card { position: static; }
  .two-col { grid-template-columns: 1fr; }
}

@media (max-width: 820px) {
  /* 移动端导航：抽屉式 */
  .nav__toggle { display: block; }

  /* 抽屉展开时给页面加一层幕布，避免下方内容干扰阅读 */
  body.nav-open::after {
    content: "";
    position: fixed;
    inset: 0;
    z-index: 50;
    background: rgba(4, 5, 7, .62);
    -webkit-backdrop-filter: blur(2px);
    backdrop-filter: blur(2px);
  }

  .nav__links {
    position: fixed;
    inset: 68px 0 auto 0;
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
    padding: 16px clamp(20px, 4vw, 40px) 28px;
    background: rgba(9, 10, 13, .98);
    backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--line);
    transform: translateY(-12px);
    opacity: 0;
    visibility: hidden;
    transition: opacity .18s ease, transform .18s ease, visibility .18s;
    max-height: calc(100dvh - 68px);
    overflow-y: auto;
  }
  .nav__links.is-open { opacity: 1; visibility: visible; transform: translateY(0); }
  .nav__links a { padding: 13px 4px; font-size: 1rem; border-bottom: 1px solid var(--line); border-radius: 0; }
  .nav__actions .btn { display: none; }
  .nav__actions .btn--nav-cta { display: inline-flex; }

  .hero__facts { grid-template-columns: 1fr; }
  .grid--4, .grid--3, .grid--2, .product-grid, .steps, .trade-list { grid-template-columns: 1fr; }
  .form-row { grid-template-columns: 1fr; }
  .footer__top { grid-template-columns: 1fr; }
  .product:hover { transform: none; }
}

@media (max-width: 520px) {
  .hero__cta .btn { width: 100%; }
  .product__actions .btn { flex: 1 1 auto; }
  .compare { border-radius: var(--radius-sm); }
  .compare th, .compare td { padding: 11px 12px; font-size: .82rem; }
}

/* 打印：只保留内容 */
@media print {
  .site-header, .hero__visual, .contact-card, .form-card { box-shadow: none; }
  body { background: #fff; color: #000; }
}

/* ============================== 14 无障碍与动效偏好 */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }
}