/* 凯尔文热控 · 企业官网 —— 按《开尔文热控企业介绍与商务方案》模板风格：
   黑色封面（太极球居中）+ 白底内页 + 红绿双色 + Noto Sans SC + 大标题极简版式 */
:root {
  --bg: #ffffff;
  --bg-2: #f6f7f9;
  --panel: #ffffff;
  --panel-2: #fafbfc;
  --line: #dee0e3;
  --txt: #1b2431;
  --muted: #5c6675;
  --red: #c0392b;
  --red-rgb: 192, 57, 43;
  --green: #2e8b57;
  --green-rgb: 46, 139, 87;
  --grad: linear-gradient(120deg, #c0392b, #2e8b57);
  --dark: #0a0a0a;
  --radius: 14px;
  --shadow: 0 14px 40px rgba(27, 36, 49, .1);
  --font: "Noto Sans SC", "Microsoft YaHei", "PingFang SC", system-ui, -apple-system, sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--txt);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }
::selection { background: rgba(var(--red-rgb), .18); }

.wrap { width: min(1180px, 92%); margin: 0 auto; }

/* ============ 导航（黑色横条） ============ */
.nav {
  position: fixed; inset: 0 0 auto 0; z-index: 100;
  background: rgba(10, 10, 10, .92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255, 255, 255, .08);
}
.nav-inner {
  width: min(1280px, 94%); margin: 0 auto;
  display: flex; align-items: center; justify-content: space-between;
  height: 66px;
}
.brand { display: flex; align-items: center; gap: 11px; color: #fff; }
.brand-mark {
  width: 38px; height: 38px; border-radius: 9px; overflow: hidden; flex: none;
  background: #000;
}
.brand-mark img { width: 100%; height: 100%; object-fit: cover; }
.brand-name { font-size: 17px; font-weight: 700; letter-spacing: .5px; }
.brand-sub { font-size: 11px; color: #8a8f98; letter-spacing: 2.5px; }
.nav-links { display: flex; gap: 6px; align-items: center; }
.nav-links a {
  padding: 8px 14px; border-radius: 8px; font-size: 14.5px; color: #b9bec7;
  transition: .2s;
}
.nav-links a:hover { color: #fff; background: rgba(255, 255, 255, .08); }
.nav-links a.active { color: #fff; background: rgba(255, 255, 255, .1); box-shadow: inset 0 -2px 0 var(--red); }
.nav-cta {
  margin-left: 10px; padding: 9px 18px !important;
  background: var(--red) !important; color: #fff !important;
  font-weight: 700; border-radius: 8px !important;
}
.nav-cta:hover { filter: brightness(1.12); }
.burger { display: none; background: none; border: 0; cursor: pointer; padding: 8px; }
.burger span { display: block; width: 22px; height: 2px; background: #fff; margin: 5px 0; border-radius: 2px; }

/* ============ 首屏（黑色封面，太极球居中） ============ */
.hero {
  position: relative; min-height: 100vh;
  display: flex; align-items: center; justify-content: center;
  background: var(--dark); overflow: hidden;
  padding: 120px 0 80px;
}
.hero::before {
  content: ""; position: absolute; inset: 0;
  background: url("../assets/opt/texture.jpg") center/cover;
  opacity: .16;
}
.hero-veil {
  position: absolute; inset: 0;
  background: radial-gradient(900px 560px at 50% 42%, rgba(0, 0, 0, .2), rgba(0, 0, 0, .82) 75%);
}
.hero-inner { position: relative; z-index: 2; text-align: center; color: #fff; }
.hero-logo {
  width: min(300px, 52vw); margin: 0 auto 30px;
  border-radius: 24px;
  box-shadow: 0 24px 70px rgba(var(--red-rgb), .22), 0 24px 70px rgba(var(--green-rgb), .18);
}
.hero-tag {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 6px 16px; border-radius: 999px;
  border: 1px solid rgba(255, 255, 255, .22);
  background: rgba(255, 255, 255, .06);
  color: #cfd4db; font-size: 13px; letter-spacing: 3px;
  margin-bottom: 24px;
}
.hero h1 {
  font-size: clamp(32px, 5vw, 58px); line-height: 1.25; font-weight: 800;
  letter-spacing: 2px;
}
.hero h1 .grad {
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero-lead {
  margin: 20px auto 0; max-width: 620px;
  color: #a7adb6; font-size: clamp(15px, 1.6vw, 17.5px);
}
.hero-btns { display: flex; gap: 14px; margin-top: 36px; justify-content: center; flex-wrap: wrap; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 13px 28px; border-radius: 10px; font-size: 15px; font-weight: 600;
  transition: .22s; border: 1px solid transparent;
}
.btn-primary { background: var(--red); color: #fff; box-shadow: 0 10px 28px rgba(var(--red-rgb), .3); }
.btn-primary:hover { transform: translateY(-2px); filter: brightness(1.1); }
.btn-ghost { border-color: rgba(255, 255, 255, .3); color: #fff; background: rgba(255, 255, 255, .04); }
.btn-ghost:hover { border-color: #fff; }

.stats {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px;
  margin-top: 60px;
}
.stat {
  background: rgba(255, 255, 255, .05); border: 1px solid rgba(255, 255, 255, .14);
  border-radius: var(--radius); padding: 20px 22px;
  backdrop-filter: blur(4px);
}
.stat b {
  display: block; font-size: clamp(24px, 2.6vw, 32px);
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text; color: transparent;
  line-height: 1.2;
}
.stat span { font-size: 13px; color: #9aa1ab; }

/* ============ 区块（白底内页） ============ */
section.sec { padding: 92px 0; position: relative; }
.sec-alt { background: var(--bg-2); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.kicker {
  display: inline-flex; align-items: center; gap: 10px;
  color: var(--red); font-size: 13px; letter-spacing: 3px; font-weight: 700;
  margin-bottom: 14px;
}
.kicker::before { content: ""; width: 26px; height: 2px; background: var(--red); border-radius: 2px; }
h2.sec-title { font-size: clamp(26px, 3.4vw, 40px); font-weight: 800; letter-spacing: 1px; }
.sec-lead { color: var(--muted); max-width: 760px; margin-top: 14px; font-size: 15.5px; }
.sec-head { margin-bottom: 50px; }

/* 卡片 */
.grid { display: grid; gap: 18px; }
.g2 { grid-template-columns: repeat(2, 1fr); }
.g3 { grid-template-columns: repeat(3, 1fr); }
.g4 { grid-template-columns: repeat(4, 1fr); }
.card {
  background: var(--panel); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 30px 26px;
  transition: .25s; position: relative; overflow: hidden;
}
.card:hover {
  transform: translateY(-5px);
  border-color: rgba(var(--red-rgb), .45);
  box-shadow: var(--shadow);
}
.ico {
  width: 52px; height: 52px; border-radius: 12px;
  display: grid; place-items: center; margin-bottom: 20px;
  background: rgba(var(--red-rgb), .08);
  border: 1px solid rgba(var(--red-rgb), .22);
  color: var(--red);
}
.ico.green { background: rgba(var(--green-rgb), .08); border-color: rgba(var(--green-rgb), .25); color: var(--green); }
.card h3 { font-size: 18.5px; margin-bottom: 10px; font-weight: 700; }
.card p { color: var(--muted); font-size: 14.5px; }
.card .num {
  position: absolute; top: 16px; right: 22px;
  font-size: 46px; font-weight: 800; color: rgba(27, 36, 49, .07);
  line-height: 1;
}

/* 图文卡 */
.pic-card {
  border: 1px solid var(--line); border-radius: var(--radius);
  overflow: hidden; background: var(--panel); transition: .25s;
}
.pic-card:hover { transform: translateY(-5px); border-color: rgba(var(--red-rgb), .45); box-shadow: var(--shadow); }
.pic-card .ph { aspect-ratio: 16 / 9; overflow: hidden; background: #f0f2f5; }
.pic-card .ph img { width: 100%; height: 100%; object-fit: cover; transition: .4s; }
.pic-card:hover .ph img { transform: scale(1.05); }
.pic-card .body { padding: 24px 24px 26px; }
.pic-card h3 { font-size: 19px; margin-bottom: 8px; }
.pic-card p { color: var(--muted); font-size: 14.5px; }
.tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
.tag {
  font-size: 12.5px; padding: 5px 12px; border-radius: 999px;
  background: rgba(var(--green-rgb), .09); color: var(--green);
  border: 1px solid rgba(var(--green-rgb), .28);
  font-weight: 600;
}

/* 引言面板 */
.quote-panel {
  border: 1px solid var(--line); border-left: 3px solid var(--red);
  background: var(--panel-2); border-radius: 0 var(--radius) var(--radius) 0;
  padding: 30px 34px;
}
.quote-panel .q-title { font-size: 20px; font-weight: 800; margin-bottom: 6px; }
.quote-panel .q-sub { color: var(--red); font-size: 14px; margin-bottom: 18px; font-weight: 600; }
.both-list { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px 26px; }
.both-list li {
  color: var(--muted); font-size: 14.5px; padding-left: 22px; position: relative;
}
.both-list li::before {
  content: "◆"; position: absolute; left: 0; top: 0;
  color: var(--red); font-size: 11px; line-height: 2.6;
}

/* 步骤 */
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.step { position: relative; padding: 30px 26px; border-radius: var(--radius); background: var(--panel); border: 1px solid var(--line); transition: .25s; }
.step:hover { border-color: rgba(var(--green-rgb), .5); transform: translateY(-4px); box-shadow: var(--shadow); }
.step .st-no {
  display: inline-grid; place-items: center; width: 44px; height: 44px;
  border-radius: 50%; font-weight: 800; font-size: 16px;
  background: var(--red); color: #fff; margin-bottom: 18px;
}

/* 表格 */
.tbl-wrap { border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; overflow-x: auto; background: var(--panel); }
table.tbl { width: 100%; border-collapse: collapse; min-width: 760px; }
.tbl th, .tbl td { padding: 13px 18px; text-align: left; font-size: 14px; border-bottom: 1px solid var(--line); }
.tbl thead th {
  background: #f2f3f5; color: var(--red);
  font-weight: 700; white-space: nowrap; letter-spacing: .5px;
}
.tbl tbody tr:last-child td { border-bottom: 0; }
.tbl tbody tr:hover { background: #faf7f6; }
.tbl td:first-child { color: var(--muted); white-space: nowrap; }

/* 产品大区块 */
.product {
  display: grid; grid-template-columns: 1.05fr 1fr; gap: 40px; align-items: center;
  padding: 44px; border: 1px solid var(--line); border-radius: 20px;
  background: var(--panel); margin-bottom: 34px;
}
.product:nth-child(even) { grid-template-columns: 1fr 1.05fr; }
.product:nth-child(even) .p-img { order: 2; }
.p-img {
  border-radius: 12px; overflow: hidden; border: 1px solid var(--line);
  background: #fff;
}
.p-img img { width: 100%; height: 100%; object-fit: cover; }
.p-img.dark { background: #101216; }
.p-badge {
  display: inline-block; padding: 5px 14px; border-radius: 999px;
  background: rgba(var(--red-rgb), .08); color: var(--red);
  font-size: 12.5px; letter-spacing: 2px; margin-bottom: 14px;
  border: 1px solid rgba(var(--red-rgb), .25); font-weight: 600;
}
.p-title { font-size: clamp(22px, 2.4vw, 30px); font-weight: 800; margin-bottom: 8px; }
.p-sub { color: var(--green); font-size: 14.5px; margin-bottom: 16px; font-weight: 600; }
.p-desc { color: var(--muted); font-size: 14.8px; }
.p-feats { margin-top: 20px; display: grid; gap: 10px; }
.p-feats li { display: flex; gap: 10px; font-size: 14.5px; color: var(--txt); }
.p-feats li svg { flex: none; margin-top: 4px; }

/* 合作伙伴 logo */
.logo-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.logo-card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  display: grid; place-items: center; padding: 30px 20px;
  min-height: 150px; transition: .25s;
}
.logo-card:hover { transform: translateY(-4px); border-color: rgba(var(--red-rgb), .45); box-shadow: var(--shadow); }
.logo-card img { max-height: 92px; object-fit: contain; }

/* CTA band（黑色收尾，呼应模板封底） */
.cta-band { position: relative; border-radius: 20px; overflow: hidden; padding: 74px 8%; text-align: center; background: var(--dark); }
.cta-band .cta-bg { position: absolute; inset: 0; background-size: cover; background-position: center; opacity: .3; }
.cta-band .cta-veil { position: absolute; inset: 0; background: radial-gradient(700px 380px at 50% 50%, rgba(0, 0, 0, .35), rgba(0, 0, 0, .85)); }
.cta-band > * { position: relative; }
.cta-band h2 { font-size: clamp(24px, 3vw, 38px); font-weight: 800; color: #fff; letter-spacing: 1px; }
.cta-band p { color: #9aa1ab; margin: 14px 0 30px; }
.cta-band .btn-ghost { border-color: rgba(255, 255, 255, .3); color: #fff; }
.cta-band .btn-ghost:hover { border-color: #fff; }

/* 页脚（黑色，呼应模板） */
footer {
  border-top: 1px solid rgba(255, 255, 255, .08);
  background: var(--dark); padding: 64px 0 0; margin-top: 40px; color: #cfd4db;
}
.f-grid { display: grid; grid-template-columns: 1.4fr 1fr 1.2fr; gap: 40px; padding-bottom: 44px; }
.f-brand p { color: #8a8f98; font-size: 14px; margin-top: 16px; max-width: 320px; }
.f-col h4 { font-size: 15px; margin-bottom: 18px; color: #fff; letter-spacing: 1px; }
.f-col a, .f-col li { display: block; color: #8a8f98; font-size: 14px; padding: 5px 0; transition: .2s; }
.f-col a:hover { color: var(--red); filter: brightness(1.6); }
.f-col li b { color: #e6e9ee; font-weight: 600; }
.f-bottom {
  border-top: 1px solid rgba(255, 255, 255, .08);
  padding: 20px 0; text-align: center; color: #6d727b; font-size: 13px;
}

/* 内页 hero */
.page-hero {
  position: relative; padding: 158px 0 64px;
  background:
    radial-gradient(700px 300px at 92% -20%, rgba(var(--red-rgb), .07), transparent 60%),
    radial-gradient(600px 300px at 4% 120%, rgba(var(--green-rgb), .08), transparent 60%),
    var(--bg);
  border-bottom: 1px solid var(--line);
}
.page-hero h1 { font-size: clamp(30px, 4vw, 46px); font-weight: 800; letter-spacing: 2px; }
.page-hero .crumbs { color: var(--muted); font-size: 13.5px; margin-top: 12px; }
.page-hero .crumbs a { color: var(--red); font-weight: 600; }
.page-hero p.lead { color: var(--muted); margin-top: 16px; max-width: 720px; }

/* 联系页 */
.contact-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.contact-card {
  display: flex; gap: 18px; align-items: flex-start;
  background: var(--panel); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 28px;
}
.contact-card .ico { margin-bottom: 0; }
.contact-card h3 { font-size: 16px; margin-bottom: 6px; }
.contact-card p { color: var(--muted); font-size: 15px; }
.contact-card a.hl { color: var(--red); font-size: 19px; font-weight: 700; }

/* 动效 */
.reveal { opacity: 0; transform: translateY(26px); transition: opacity .7s ease, transform .7s ease; }
.reveal.in { opacity: 1; transform: none; }
.d1 { transition-delay: .08s; } .d2 { transition-delay: .16s; } .d3 { transition-delay: .24s; } .d4 { transition-delay: .32s; }

@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
}

/* 响应式 */
@media (max-width: 1024px) {
  .g4 { grid-template-columns: repeat(2, 1fr); }
  .product, .product:nth-child(even) { grid-template-columns: 1fr; padding: 28px; }
  .product:nth-child(even) .p-img { order: 0; }
  .stats { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 760px) {
  .nav-links {
    position: fixed; top: 66px; right: 0; left: 0;
    flex-direction: column; align-items: stretch; gap: 0;
    background: rgba(10, 10, 10, .97); border-bottom: 1px solid rgba(255, 255, 255, .08);
    padding: 10px 5%;
    display: none;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 13px 10px; border-radius: 8px; }
  .burger { display: block; }
  .g2, .g3, .g4, .steps, .contact-grid, .both-list, .logo-row { grid-template-columns: 1fr; }
  .f-grid { grid-template-columns: 1fr; gap: 26px; }
  section.sec { padding: 64px 0; }
  .hero { min-height: auto; padding: 110px 0 64px; }
  .quote-panel { padding: 24px 22px; }
}