/* =========================================================
   North China Source — site styles
   Industrial B2B design system: navy + amber, blueprint grid
   ========================================================= */

:root {
  --ink: #0d1b2e;
  --navy: #122a4d;
  --navy-deep: #0b1d38;
  --blue: #1d5ec2;
  --blue-soft: #e8f0fc;
  --amber: #f5a623;
  --amber-deep: #b97c08;
  --steel: #5b6b7d;
  --line: #e2e8f1;
  --bg: #f4f7fb;
  --card: #ffffff;
  --ok: #1e9e5a;
  --err: #c0392b;
  --rad: 14px;
  --shadow: 0 10px 30px rgba(13, 27, 46, .08);
  --shadow-lg: 0 18px 44px rgba(13, 27, 46, .14);
}

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

html { scroll-behavior: smooth; }

body {
  font-family: "Segoe UI", system-ui, -apple-system, "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img, svg { display: block; max-width: 100%; }
a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; }
ul { list-style: none; }

.container { width: min(1120px, 92%); margin: 0 auto; }

/* ---------- Buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 700;
  font-size: 15px;
  line-height: 1;
  border-radius: 10px;
  padding: 14px 28px;
  border: 2px solid transparent;
  cursor: pointer;
  transition: transform .2s ease, background .2s ease, box-shadow .2s ease, color .2s ease;
  text-decoration: none;
}
.btn:hover { text-decoration: none; }

.btn-primary {
  background: var(--amber);
  color: #231a06;
  box-shadow: 0 10px 24px rgba(245, 166, 35, .35);
}
.btn-primary:hover { background: #ffb937; transform: translateY(-2px); box-shadow: 0 14px 30px rgba(245, 166, 35, .42); }

.btn-ghost { border-color: rgba(255, 255, 255, .55); color: #fff; }
.btn-ghost:hover { border-color: #fff; background: rgba(255, 255, 255, .08); }

.btn-navy { border-color: var(--navy); color: var(--navy); background: #fff; }
.btn-navy:hover { background: var(--navy); color: #fff; }

.btn-sm { padding: 10px 20px; font-size: 13.5px; }

/* ---------- Header ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: rgba(255, 255, 255, .94);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
  transition: box-shadow .25s ease;
}
.site-header.scrolled { box-shadow: 0 8px 26px rgba(13, 27, 46, .09); }

.header-inner { display: flex; align-items: center; justify-content: space-between; height: 74px; gap: 20px; }

.brand { display: flex; align-items: center; gap: 11px; color: var(--ink); flex: 0 0 auto; }
.brand:hover { text-decoration: none; }
.brand-mark { width: 40px; height: 40px; }
.brand-name { font-weight: 800; font-size: 16.5px; letter-spacing: .01em; line-height: 1.2; }
.brand-name small {
  display: block;
  font-weight: 700;
  font-size: 10px;
  letter-spacing: .26em;
  color: var(--steel);
  text-transform: uppercase;
  margin-top: 2px;
}

.site-nav { display: flex; align-items: center; gap: 28px; }
.nav-link { color: var(--steel); font-weight: 600; font-size: 14.5px; }
.nav-link:hover { color: var(--ink); text-decoration: none; }
.nav-link.active { color: var(--ink); }
.nav-cta { background: var(--amber); color: #231a06; font-weight: 700; font-size: 13.5px; padding: 11px 20px; border-radius: 9px; box-shadow: 0 6px 16px rgba(245, 166, 35, .3); }
.nav-cta:hover { background: #ffb937; text-decoration: none; }

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  border: 1px solid var(--line);
  background: #fff;
  border-radius: 10px;
  cursor: pointer;
  padding: 11px;
}
.nav-toggle span { display: block; height: 2.5px; background: var(--ink); border-radius: 2px; margin: 4.5px 0; transition: .2s; }

@media (max-width: 880px) {
  .nav-toggle { display: block; }
  .site-nav {
    display: none;
    position: absolute;
    top: 74px;
    left: 0;
    right: 0;
    background: #fff;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 10px 4% 20px;
    border-bottom: 1px solid var(--line);
    box-shadow: 0 20px 40px rgba(13, 27, 46, .12);
  }
  .site-nav.open { display: flex; }
  .site-nav .nav-link { padding: 13px 4px; border-bottom: 1px solid var(--line); }
  .site-nav .nav-cta { margin-top: 14px; text-align: center; }
}

/* ---------- Hero (home) ---------- */

.hero {
  position: relative;
  color: #fff;
  padding: 92px 0 104px;
  background: linear-gradient(180deg, var(--navy-deep), var(--navy));
  overflow: hidden;
}
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, .05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, .05) 1px, transparent 1px);
  background-size: 44px 44px;
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, .95), transparent 78%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, .95), transparent 78%);
}
.hero::after {
  content: "";
  position: absolute;
  width: 780px;
  height: 780px;
  border-radius: 50%;
  right: -240px;
  top: -300px;
  background: radial-gradient(closest-side, rgba(29, 94, 194, .4), transparent 70%);
  pointer-events: none;
}

.hero-grid { position: relative; display: grid; grid-template-columns: 1.12fr .88fr; gap: 56px; align-items: center; z-index: 1; }

.eyebrow {
  display: inline-block;
  font-size: 11.5px;
  font-weight: 800;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: 18px;
}

.hero h1 {
  font-size: clamp(30px, 4.6vw, 50px);
  line-height: 1.13;
  font-weight: 800;
  letter-spacing: -.015em;
}
.hero .lead {
  margin: 22px 0 34px;
  font-size: 16.5px;
  color: rgba(255, 255, 255, .84);
  max-width: 58ch;
}
.hero-ctas { display: flex; gap: 14px; flex-wrap: wrap; }

.hero-figure { position: relative; }
.hero-figure svg { width: 100%; height: auto; }

@media (max-width: 920px) {
  .hero-grid { grid-template-columns: 1fr; gap: 40px; }
  .hero-figure { max-width: 520px; }
}

/* ---------- Stats strip ---------- */

.stats { background: var(--navy-deep); border-top: 1px solid rgba(255, 255, 255, .08); color: #fff; }
.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); }
.stat { padding: 30px 22px; text-align: center; border-left: 1px solid rgba(255, 255, 255, .08); }
.stat:first-child { border-left: none; }
.stat b { display: block; font-size: 30px; font-weight: 800; color: var(--amber); letter-spacing: -.01em; }
.stat span { font-size: 13px; color: rgba(255, 255, 255, .68); font-weight: 600; letter-spacing: .04em; }
@media (max-width: 760px) {
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .stat:nth-child(3) { border-left: none; }
  .stat:nth-child(n+3) { border-top: 1px solid rgba(255, 255, 255, .08); }
}

/* ---------- Sections ---------- */

.section { padding: 86px 0; }
.section.alt { background: #fff; }

.section-head { max-width: 740px; margin: 0 auto 48px; text-align: center; }
.section-head .eyebrow { color: var(--amber-deep); }
.section-head h2 { font-size: clamp(24px, 3.4vw, 35px); font-weight: 800; letter-spacing: -.012em; line-height: 1.2; }
.section-head p { margin-top: 14px; color: var(--steel); font-size: 16px; }

/* ---------- Cards & grids ---------- */

.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 22px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }

@media (max-width: 980px) {
  .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 620px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--rad);
  padding: 28px;
  box-shadow: var(--shadow);
  transition: transform .25s ease, box-shadow .25s ease;
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}
.card::before {
  content: "";
  position: absolute;
  top: 0; left: 26px; right: 26px;
  height: 3px;
  border-radius: 3px;
  background: linear-gradient(90deg, var(--amber), rgba(245, 166, 35, 0));
  opacity: 0;
  transition: opacity .25s ease;
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.card:hover::before { opacity: 1; }

.card h3 { font-size: 18.5px; font-weight: 800; letter-spacing: -.008em; }
.card p { color: var(--steel); font-size: 14.5px; margin-top: 10px; flex: 1; }

.icon-badge {
  width: 52px;
  height: 52px;
  border-radius: 13px;
  background: var(--blue-soft);
  color: var(--blue);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 18px;
  flex: 0 0 auto;
}
.icon-badge svg { width: 26px; height: 26px; }

.chips { display: flex; flex-wrap: wrap; gap: 8px; margin: 16px 0 20px; }
.chip {
  background: var(--bg);
  border: 1px solid var(--line);
  color: var(--steel);
  font-size: 12.5px;
  font-weight: 600;
  padding: 5px 12px;
  border-radius: 999px;
}

.card-link {
  font-weight: 700;
  font-size: 14px;
  color: var(--blue);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-top: 4px;
}
.card-link:hover { text-decoration: underline; }

/* ---------- Category cards (products) ---------- */

.cat-card { padding: 24px; }
.cat-card .cluster-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  font-weight: 700;
  color: var(--amber-deep);
  letter-spacing: .06em;
  text-transform: uppercase;
  margin-bottom: 12px;
}
.cat-card .cluster-tag svg { width: 13px; height: 13px; }
.cat-card h3 { font-size: 17.5px; }
.cat-card p { font-size: 14px; }
.cat-card .specs {
  border-top: 1px dashed var(--line);
  margin-top: 16px;
  padding-top: 12px;
  font-size: 12.5px;
  color: var(--steel);
  font-weight: 600;
  letter-spacing: .01em;
}

/* ---------- Dark cluster band ---------- */

.cluster-band { background: var(--navy-deep); color: #fff; padding: 86px 0; position: relative; overflow: hidden; }
.cluster-band::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, .035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, .035) 1px, transparent 1px);
  background-size: 44px 44px;
}
.cluster-band .container { position: relative; }
.cluster-band .section-head h2 { color: #fff; }
.cluster-band .section-head .eyebrow { color: var(--amber); }
.cluster-band .section-head p { color: rgba(255, 255, 255, .7); }

.cluster-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
@media (max-width: 920px) { .cluster-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 600px) { .cluster-grid { grid-template-columns: 1fr; } }

.cluster-card {
  background: rgba(255, 255, 255, .05);
  border: 1px solid rgba(255, 255, 255, .13);
  border-radius: 12px;
  padding: 20px 22px;
  transition: background .2s ease, border-color .2s ease;
}
.cluster-card:hover { background: rgba(255, 255, 255, .09); border-color: rgba(245, 166, 35, .5); }
.cluster-card b { display: block; font-size: 15.5px; color: #fff; }
.cluster-card b .zh { color: var(--amber); font-size: 12.5px; font-weight: 600; margin-left: 7px; }
.cluster-card span { display: block; font-size: 13px; color: rgba(255, 255, 255, .66); margin-top: 4px; }

/* ---------- Process steps ---------- */

.steps { display: grid; grid-template-columns: repeat(5, 1fr); gap: 18px; }
@media (max-width: 980px) { .steps { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .steps { grid-template-columns: 1fr; } }

.step { text-align: center; padding: 10px 6px; }
.step-num {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: var(--navy);
  color: #fff;
  font-weight: 800;
  font-size: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 14px;
  box-shadow: 0 8px 18px rgba(18, 42, 77, .28);
}
.step b { display: block; font-size: 15px; }
.step span { display: block; font-size: 13px; color: var(--steel); margin-top: 6px; }

/* ---------- CTA band ---------- */

.cta-band {
  background:
    radial-gradient(800px 300px at 20% 0%, rgba(29, 94, 194, .5), transparent 60%),
    linear-gradient(120deg, var(--navy-deep), #1c3f74 75%);
  color: #fff;
  text-align: center;
  padding: 78px 0;
}
.cta-band h2 { font-size: clamp(23px, 3.2vw, 32px); font-weight: 800; letter-spacing: -.01em; }
.cta-band p { color: rgba(255, 255, 255, .78); margin: 14px 0 30px; }

/* ---------- Page hero (subpages) ---------- */

.page-hero {
  position: relative;
  background: linear-gradient(180deg, var(--navy-deep), var(--navy));
  color: #fff;
  padding: 62px 0 58px;
  overflow: hidden;
}
.page-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, .05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, .05) 1px, transparent 1px);
  background-size: 44px 44px;
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, .95), transparent 80%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, .95), transparent 80%);
}
.page-hero .container { position: relative; }
.page-hero h1 { font-size: clamp(26px, 3.8vw, 40px); font-weight: 800; letter-spacing: -.012em; }
.page-hero p { color: rgba(255, 255, 255, .8); margin-top: 12px; max-width: 74ch; font-size: 16px; }

/* ---------- Group blocks (products page) ---------- */

.group-block { padding: 56px 0; border-top: 1px solid var(--line); }
.group-block:first-of-type { border-top: none; padding-top: 10px; }
.group-head { display: flex; align-items: flex-start; gap: 18px; margin-bottom: 30px; }
.group-head .icon-badge { margin-bottom: 0; }
.group-head h2 { font-size: clamp(21px, 2.8vw, 28px); font-weight: 800; letter-spacing: -.01em; }
.group-head p { color: var(--steel); font-size: 14.5px; margin-top: 6px; max-width: 70ch; }

/* ---------- Contact form ---------- */

.contact-grid { display: grid; grid-template-columns: 1.35fr .65fr; gap: 40px; align-items: start; }
@media (max-width: 900px) { .contact-grid { grid-template-columns: 1fr; } }

.form-card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--rad);
  padding: 34px;
  box-shadow: var(--shadow);
}
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.field { display: flex; flex-direction: column; gap: 7px; }
.field.full { grid-column: 1 / -1; }
@media (max-width: 640px) { .form-grid { grid-template-columns: 1fr; } }

.field label { font-weight: 700; font-size: 13.5px; }
.field label em { color: var(--amber-deep); font-style: normal; }

.field input, .field select, .field textarea {
  border: 1.5px solid var(--line);
  border-radius: 10px;
  padding: 12px 14px;
  font: inherit;
  font-size: 14.5px;
  background: #fff;
  color: var(--ink);
  transition: border-color .2s ease, box-shadow .2s ease;
  width: 100%;
}
.field textarea { min-height: 140px; resize: vertical; }
.field input:focus, .field select:focus, .field textarea:focus {
  outline: none;
  border-color: var(--blue);
  box-shadow: 0 0 0 4px rgba(29, 94, 194, .13);
}

.honeypot { position: absolute; left: -9999px; top: -9999px; }

.form-status { margin-top: 16px; font-size: 14.5px; font-weight: 600; display: none; }
.form-status.success { display: block; color: var(--ok); }
.form-status.error { display: block; color: var(--err); }

.side-card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--rad);
  padding: 26px;
  box-shadow: var(--shadow);
  margin-bottom: 20px;
}
.side-card h3 { font-size: 16px; font-weight: 800; margin-bottom: 12px; }
.side-card p, .side-card li { font-size: 14px; color: var(--steel); }
.side-card a { font-weight: 600; }
.side-card ul { display: grid; gap: 9px; margin-top: 6px; }
.side-card ul li { display: flex; gap: 9px; align-items: flex-start; }
.side-card ul svg { width: 17px; height: 17px; color: var(--ok); flex: 0 0 auto; margin-top: 3px; }

/* ---------- Footer ---------- */

.site-footer { background: #0a1830; color: rgba(255, 255, 255, .72); padding: 58px 0 30px; font-size: 14px; }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1.1fr; gap: 40px; margin-bottom: 42px; }
@media (max-width: 880px) { .footer-grid { grid-template-columns: 1fr; gap: 30px; } }

.site-footer .brand-name { color: #fff; }
.site-footer .brand-name small { color: rgba(255, 255, 255, .45); }
.footer-blurb { margin-top: 16px; font-size: 13.5px; color: rgba(255, 255, 255, .55); max-width: 42ch; }

.site-footer h4 { color: #fff; font-size: 13px; font-weight: 800; letter-spacing: .14em; text-transform: uppercase; margin-bottom: 16px; }
.footer-links { display: grid; gap: 10px; }
.footer-links a { color: rgba(255, 255, 255, .68); font-size: 14px; }
.footer-links a:hover { color: #fff; text-decoration: none; }

.footer-contact li { display: flex; gap: 10px; align-items: flex-start; margin-bottom: 11px; }
.footer-contact svg { width: 16px; height: 16px; color: var(--amber); flex: 0 0 auto; margin-top: 4px; }
.footer-contact a { color: rgba(255, 255, 255, .8); }
.footer-contact a:hover { color: #fff; }

.footer-bottom { border-top: 1px solid rgba(255, 255, 255, .1); padding-top: 24px; display: flex; justify-content: space-between; gap: 14px; flex-wrap: wrap; font-size: 13px; color: rgba(255, 255, 255, .45); }

/* ---------- Reveal animation ---------- */

.reveal { opacity: 0; transform: translateY(18px); transition: opacity .6s ease, transform .6s ease; }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  html { scroll-behavior: auto; }
}

/* ---------- Misc ---------- */

.text-center { text-align: center; }
.mt-30 { margin-top: 30px; }
.note { font-size: 13px; color: var(--steel); }

/* ---------- Photography ---------- */

.card-img {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
  margin: -28px -28px 20px;
  background: var(--blue-soft);
}
.cat-card .card-img { margin: -24px -24px 18px; }

.hero-mosaic {
  display: grid;
  grid-template-columns: 1.16fr 1fr 1fr 1.06fr;
  grid-template-rows: 172px 192px;
  grid-template-areas:
    "mesh flng flng bolt"
    "mesh bags pail stmp";
  gap: 12px;
  border-radius: 18px;
  border: 1px solid rgba(255, 255, 255, .16);
  box-shadow: 0 30px 70px rgba(3, 10, 24, .55);
  overflow: hidden;
  background: var(--blue-soft);
}
.hero-mosaic img { width: 100%; height: 100%; object-fit: cover; display: block; }
.hero-mosaic .m-mesh { grid-area: mesh; }
.hero-mosaic .m-flng { grid-area: flng; }
.hero-mosaic .m-bolt { grid-area: bolt; }
.hero-mosaic .m-bags { grid-area: bags; }
.hero-mosaic .m-pail { grid-area: pail; }
.hero-mosaic .m-stmp { grid-area: stmp; }

@media (max-width: 600px) {
  .hero-mosaic {
    grid-template-columns: 1.12fr 1fr;
    grid-template-rows: repeat(3, 132px);
    grid-template-areas:
      "mesh flng"
      "mesh bolt"
      "bags pail";
  }
  .hero-mosaic .m-stmp { display: none; }
}

.hero-badge {
  position: absolute;
  left: 20px;
  bottom: 20px;
  display: flex;
  align-items: center;
  gap: 11px;
  background: rgba(8, 20, 42, .82);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  border: 1px solid rgba(255, 255, 255, .16);
  border-radius: 12px;
  padding: 12px 16px;
  color: #fff;
  box-shadow: 0 14px 34px rgba(3, 10, 24, .4);
}
.hero-badge svg { width: 26px; height: 26px; color: var(--amber); flex: 0 0 auto; }
.hero-badge b { display: block; font-size: 14px; font-weight: 800; line-height: 1.25; }
.hero-badge span { display: block; font-size: 12px; color: rgba(255, 255, 255, .68); margin-top: 2px; }

.section-figure {
  margin: 0 auto 44px;
  max-width: 860px;
  border-radius: var(--rad);
  overflow: hidden;
  border: 1px solid var(--line);
  box-shadow: var(--shadow-lg);
}
.section-figure img { width: 100%; display: block; aspect-ratio: 21 / 9; object-fit: cover; }

.cluster-map { max-width: 640px; margin: 0 auto 46px; position: relative; }
.cluster-map svg { width: 100%; height: auto; }