/* ==========================================================================
   HY-PART — Hydrogen Fuel Cell Component Sourcing
   Design system: industrial, high-trust, conversion-focused
   ========================================================================== */

:root {
  /* Brand — sampled from official HY-PART logo */
  --brand-blue: #2FB4FF;
  --brand-blue-deep: #0A7FC4;
  --brand-green: #37B82A;
  --brand-green-deep: #2A8C20;
  --brand-gradient: linear-gradient(135deg, #2FB4FF 0%, #37B82A 100%);

  /* Ink / primary action */
  --navy: #12303F;
  --navy-dark: #0B2029;
  --blue: #0A7FC4;
  --teal: #37B82A;
  --teal-dark: #2A8C20;

  /* Neutrals */
  --ink: #12212B;
  --body: #445566;
  --muted: #6B7C8C;
  --line: #E3EAF0;
  --line-soft: #EEF3F7;
  --bg: #FFFFFF;
  --bg-soft: #F6F9FB;
  --bg-navy: #12303F;

  /* Type scale */
  --fs-xs: 0.8125rem;
  --fs-sm: 0.9375rem;
  --fs-base: 1rem;
  --fs-md: 1.0625rem;
  --fs-lg: 1.25rem;
  --fs-xl: 1.5rem;
  --fs-2xl: 2rem;
  --fs-3xl: 2.75rem;

  --radius: 10px;
  --radius-lg: 14px;
  --maxw: 1160px;
  --shadow-sm: 0 1px 2px rgba(18, 48, 63, 0.06);
  --shadow: 0 4px 16px rgba(18, 48, 63, 0.08);
  --shadow-lg: 0 12px 40px rgba(18, 48, 63, 0.12);
}

*, *::before, *::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
               "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  font-size: var(--fs-base);
  line-height: 1.65;
  color: var(--body);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  color: var(--ink);
  line-height: 1.25;
  margin: 0 0 0.5em;
  font-weight: 650;
  letter-spacing: -0.015em;
}

h1 { font-size: var(--fs-3xl); }
h2 { font-size: var(--fs-2xl); }
h3 { font-size: var(--fs-lg); }
h4 { font-size: var(--fs-md); }

p { margin: 0 0 1rem; }

a { color: var(--blue); text-decoration: none; }
a:hover { color: var(--navy); text-decoration: underline; }

img { max-width: 100%; height: auto; }

.container {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--navy);
  color: #fff;
  padding: 12px 20px;
  z-index: 200;
}
.skip-link:focus { left: 0; }

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
  gap: 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 11px;
  flex-shrink: 0;
}
.brand:hover { text-decoration: none; }

/* 官方 LOGO 图片 */
.brand-logo {
  height: 38px;
  width: auto;
  display: block;
}
.brand-logo--mark { height: 34px; }

.brand-text { display: flex; flex-direction: column; }
.brand-name {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--navy);
  letter-spacing: -0.02em;
  line-height: 1.1;
}
.brand-sub {
  font-size: 0.6875rem;
  color: var(--muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-weight: 600;
}
.site-footer .brand-logo { height: 34px; }

.nav {
  display: flex;
  align-items: center;
  gap: 30px;
}
.nav a {
  color: var(--body);
  font-size: var(--fs-sm);
  font-weight: 500;
  padding: 6px 0;
  border-bottom: 2px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}
.nav a:hover, .nav a.active {
  color: var(--navy);
  text-decoration: none;
  border-bottom-color: var(--teal);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 20px;
  border-radius: 8px;
  font-size: var(--fs-sm);
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background 0.15s, color 0.15s, border-color 0.15s, transform 0.1s;
  white-space: nowrap;
}
.btn:hover { text-decoration: none; transform: translateY(-1px); }
.btn-primary { background: var(--navy); color: #fff; }
.btn-primary:hover { background: var(--navy-dark); color: #fff; }
.btn-accent { background: var(--teal); color: #fff; }
.btn-accent:hover { background: var(--teal-dark); color: #fff; }
.btn-ghost { border-color: var(--line); color: var(--navy); background: #fff; }
.btn-ghost:hover { border-color: var(--navy); color: var(--navy); }
.btn-lg { padding: 14px 26px; font-size: var(--fs-base); }

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--line);
  border-radius: 8px;
  width: 42px;
  height: 42px;
  cursor: pointer;
  align-items: center;
  justify-content: center;
}

/* ---------- Hero ---------- */
.hero {
  background: var(--bg-soft);
  border-bottom: 1px solid var(--line);
  padding: 76px 0 68px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -180px;
  right: -140px;
  width: 520px;
  height: 520px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(47, 180, 255, 0.14) 0%, rgba(55, 184, 42, 0.08) 45%, transparent 70%);
  pointer-events: none;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 56px;
  align-items: center;
  position: relative;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: var(--fs-xs);
  font-weight: 650;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--teal-dark);
  background: rgba(47, 180, 255, 0.10);
  border: 1px solid rgba(55, 184, 42, 0.30);
  padding: 6px 14px;
  border-radius: 100px;
  margin-bottom: 22px;
}

.hero h1 {
  font-size: clamp(2rem, 4.2vw, 3rem);
  margin-bottom: 20px;
  letter-spacing: -0.028em;
}

.hero h1 em {
  font-style: normal;
  color: var(--teal-dark);
}

.hero-lead {
  font-size: var(--fs-md);
  color: var(--body);
  max-width: 54ch;
  margin-bottom: 30px;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  margin-bottom: 28px;
}

.hero-facts {
  display: flex;
  gap: 36px;
  flex-wrap: wrap;
  padding-top: 26px;
  border-top: 1px solid var(--line);
}
.hero-fact-value {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--navy);
  line-height: 1.1;
  letter-spacing: -0.02em;
}
.hero-fact-label {
  font-size: var(--fs-xs);
  color: var(--muted);
  margin-top: 3px;
}

/* Hero spec card */
.spec-card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}
.spec-card-head {
  background: var(--bg-navy);
  color: #fff;
  padding: 14px 20px;
  font-size: var(--fs-sm);
  font-weight: 650;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.spec-card-head span { opacity: 0.72; font-weight: 500; font-size: var(--fs-xs); }
.spec-card-body { padding: 6px 20px 14px; }

.spec-row {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 11px 0;
  border-bottom: 1px solid var(--line-soft);
  font-size: var(--fs-sm);
}
.spec-row:last-child { border-bottom: none; }
.spec-row dt { color: var(--muted); margin: 0; }
.spec-row dd {
  margin: 0;
  color: var(--ink);
  font-weight: 600;
  text-align: right;
  font-variant-numeric: tabular-nums;
}

/* ---------- Sections ---------- */
.section { padding: 76px 0; }
.section-sm { padding: 52px 0; }
.section-alt { background: var(--bg-soft); }

.section-head { max-width: 680px; margin-bottom: 46px; }
.section-head.center { margin-left: auto; margin-right: auto; text-align: center; }
.section-head h2 { margin-bottom: 14px; }
.section-head p { color: var(--muted); font-size: var(--fs-md); margin: 0; }

/* ---------- Grid & cards ---------- */
.grid { display: grid; gap: 22px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

.card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 26px;
  transition: border-color 0.18s, box-shadow 0.18s, transform 0.18s;
  display: flex;
  flex-direction: column;
}
.card:hover {
  border-color: var(--brand-blue);
  box-shadow: 0 6px 24px rgba(47, 180, 255, 0.14);
  transform: translateY(-2px);
}
.card h3 { font-size: var(--fs-md); margin-bottom: 8px; }
.card h3 a { color: inherit; }
.card h3 a::after { content: ""; position: absolute; inset: 0; }
.card p { font-size: var(--fs-sm); color: var(--muted); margin: 0; }
.card-link {
  margin-top: 14px;
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--teal-dark);
  display: inline-flex;
  align-items: center;
  gap: 5px;
}

.card-icon {
  width: 44px;
  height: 44px;
  border-radius: 11px;
  background: var(--brand-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  flex-shrink: 0;
  color: #fff;
}

.card { position: relative; }

/* ---------- Tables ---------- */
.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: #fff;
  -webkit-overflow-scrolling: touch;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--fs-sm);
  min-width: 560px;
}

thead th {
  background: var(--bg-navy);
  color: #fff;
  text-align: left;
  padding: 14px 18px;
  font-weight: 600;
  font-size: var(--fs-sm);
  white-space: nowrap;
}
thead th:first-child { border-radius: var(--radius) 0 0 0; }
thead th:last-child { border-radius: 0 var(--radius) 0 0; }

tbody td {
  padding: 13px 18px;
  border-bottom: 1px solid var(--line-soft);
  color: var(--body);
  vertical-align: top;
}
tbody tr:last-child td { border-bottom: none; }
tbody tr:hover { background: var(--bg-soft); }
tbody td:first-child { color: var(--ink); font-weight: 600; }
table.compact td, table.compact th { padding: 10px 14px; font-size: var(--fs-xs); }

/* ---------- Page hero (interior) ---------- */
.page-hero {
  background: var(--bg-soft);
  border-bottom: 1px solid var(--line);
  padding: 54px 0 48px;
}
.page-hero h1 { font-size: clamp(1.8rem, 3.4vw, 2.4rem); margin-bottom: 14px; }
.page-hero .lead {
  font-size: var(--fs-md);
  color: var(--body);
  max-width: 68ch;
  margin: 0;
}

.breadcrumb {
  font-size: var(--fs-xs);
  color: var(--muted);
  margin-bottom: 18px;
}
.breadcrumb a { color: var(--muted); }
.breadcrumb span { margin: 0 7px; opacity: 0.5; }

/* ---------- Prose ---------- */
.prose { max-width: 100%; }
.prose h2 {
  font-size: var(--fs-xl);
  margin: 44px 0 16px;
  padding-top: 4px;
}
.prose h3 { font-size: var(--fs-md); margin: 30px 0 10px; }
.prose p { margin-bottom: 1.1rem; }
.prose ul, .prose ol { margin: 0 0 1.2rem; padding-left: 22px; }
.prose li { margin-bottom: 0.5rem; }
.prose strong { color: var(--ink); font-weight: 650; }
.prose > *:first-child { margin-top: 0; }

/* ---------- Feature list ---------- */
.feature-list { list-style: none; padding: 0; margin: 0; }
.feature-list li {
  display: flex;
  gap: 12px;
  margin-bottom: 13px;
  font-size: var(--fs-sm);
  line-height: 1.6;
}
.feature-list li::before {
  content: "";
  flex-shrink: 0;
  width: 18px;
  height: 18px;
  margin-top: 2px;
  border-radius: 50%;
  background: rgba(55, 184, 42, 0.14)
    url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%232A8C20' stroke-width='3.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='20 6 9 17 4 12'/%3E%3C/svg%3E")
    center / 11px no-repeat;
}

/* ---------- Callout ---------- */
.callout {
  background: var(--bg-soft);
  border-left: 3px solid var(--teal);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 20px 24px;
  margin: 26px 0;
}
.callout p:last-child { margin-bottom: 0; }
.callout strong { color: var(--ink); }

/* ---------- FAQ ---------- */
.faq { border-top: 1px solid var(--line); }
.faq-item { border-bottom: 1px solid var(--line); }
.faq-q {
  font-weight: 650;
  color: var(--ink);
  padding: 18px 34px 18px 0;
  position: relative;
  cursor: pointer;
  font-size: var(--fs-md);
  list-style: none;
}
.faq-q::-webkit-details-marker { display: none; }
.faq-q::after {
  content: "+";
  position: absolute;
  right: 6px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--teal-dark);
  font-size: 1.4rem;
  font-weight: 400;
  line-height: 1;
}
.faq-item[open] .faq-q::after { content: "\2212"; }
.faq-a {
  padding: 0 0 20px;
  font-size: var(--fs-sm);
  color: var(--body);
  max-width: 74ch;
}

/* ---------- CTA ---------- */
.cta-band {
  background: var(--bg-navy);
  color: #fff;
  padding: 56px 0;
}
.cta-band h2 { color: #fff; margin-bottom: 12px; }
.cta-band p { color: rgba(255,255,255,0.82); max-width: 60ch; margin-bottom: 26px; }
.cta-inner { display: flex; justify-content: space-between; align-items: center; gap: 40px; flex-wrap: wrap; }
.cta-actions { display: flex; gap: 12px; flex-wrap: wrap; }

/* ---------- Footer ---------- */
.site-footer {
  background: #12303F;
  color: rgba(255,255,255,0.70);
  padding: 54px 0 26px;
  font-size: var(--fs-sm);
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1.2fr;
  gap: 40px;
  padding-bottom: 34px;
  border-bottom: 1px solid rgba(255,255,255,0.11);
}
.site-footer h4 {
  color: #fff;
  font-size: var(--fs-xs);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 14px;
  font-weight: 650;
}
.site-footer a { color: rgba(255,255,255,0.72); }
.site-footer a:hover { color: #fff; }
.footer-links { list-style: none; padding: 0; margin: 0; }
.footer-links li { margin-bottom: 9px; }
.footer-brand .brand-name { color: #fff; }
.footer-brand .brand-sub { color: rgba(255,255,255,0.5); }
.footer-bottom {
  padding-top: 22px;
  display: flex;
  justify-content: space-between;
  gap: 18px;
  flex-wrap: wrap;
  font-size: var(--fs-xs);
  color: rgba(255,255,255,0.45);
}

/* ---------- Utility ---------- */
.text-center { text-align: center; }
.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }
.lead-lg { font-size: var(--fs-md); color: var(--muted); }
.stack > * + * { margin-top: 14px; }
.hide-sm { display: initial; }

.section-label {
  font-size: var(--fs-xs);
  font-weight: 650;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--teal-dark);
  margin-bottom: 12px;
  display: block;
}

.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 52px;
  align-items: start;
}

.stat-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.stat {
  background: #fff;
  padding: 26px 22px;
  text-align: center;
}
.stat-value {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--navy);
  letter-spacing: -0.02em;
  line-height: 1.1;
}
.stat-label {
  font-size: var(--fs-xs);
  color: var(--muted);
  margin-top: 5px;
}

/* ---------- Responsive ---------- */
@media (max-width: 1000px) {
  .hero-grid { grid-template-columns: 1fr; gap: 40px; }
  .grid-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
  .split { grid-template-columns: 1fr; gap: 32px; }
  .stat-row { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 760px) {
  h1 { font-size: 1.9rem; }
  .section { padding: 54px 0; }
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .hero { padding: 50px 0 46px; }
  .hero-facts { gap: 24px; }
  .hero-fact-value { font-size: 1.3rem; }
  .cta-actions .btn { flex: 1; justify-content: center; }
  .hide-sm { display: none; }

  .nav {
    display: none;
    position: absolute;
    top: 72px;
    left: 0;
    right: 0;
    background: #fff;
    border-bottom: 1px solid var(--line);
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 8px 24px 18px;
    box-shadow: var(--shadow);
  }
  .nav.open { display: flex; }
  .nav a { padding: 12px 0; border-bottom: 1px solid var(--line-soft); }
  .nav .btn { margin-top: 14px; justify-content: center; }
  .nav-toggle { display: flex; }
  .header-inner { position: relative; }

  .footer-grid { grid-template-columns: 1fr; }
  .footer-bottom { flex-direction: column; gap: 8px; }
}

@media (max-width: 480px) {
  .grid-4 { grid-template-columns: 1fr; }
  .stat-row { grid-template-columns: 1fr; }
  .container { padding: 0 18px; }
}

@media print {
  .site-header, .cta-band, .site-footer, .nav-toggle { display: none; }
  body { font-size: 11pt; }
}