/* ============================================================
   Haiyue Shengda — Electric Heating Products
   Global stylesheet (self-contained, no external dependencies)
   ============================================================ */

:root {
  --navy: #10263f;
  --navy-2: #1a3a5c;
  --navy-3: #27496e;
  --ember: #e2542f;
  --ember-light: #f27a4a;
  --ember-soft: #fdeee7;
  --cream: #faf5ef;
  --ink: #22303c;
  --grey: #6b7683;
  --grey-light: #e8e3dc;
  --white: #ffffff;
  --line: #e3ded6;
  --shadow: 0 10px 30px rgba(16, 38, 63, 0.08);
  --shadow-lg: 0 18px 50px rgba(16, 38, 63, 0.14);
  --radius: 14px;
  --radius-sm: 8px;
  --container: 1180px;
  --font: "Segoe UI", "Helvetica Neue", Helvetica, Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  color: var(--ink);
  background: var(--white);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; display: block; }
a { color: var(--ember); text-decoration: none; transition: color .2s; }
a:hover { color: var(--navy); }

h1, h2, h3, h4 { color: var(--navy); line-height: 1.25; font-weight: 800; letter-spacing: -0.01em; }
h1 { font-size: clamp(2rem, 4.2vw, 3.2rem); }
h2 { font-size: clamp(1.6rem, 3vw, 2.3rem); }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.05rem; }

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

.section { padding: 84px 0; }
.section-cream { background: var(--cream); }
.section-navy { background: var(--navy); }
.section-navy h2, .section-navy h3, .section-navy p { color: #fff; }
.section-navy .muted { color: #b9c6d6; }

.kicker {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ember);
  margin-bottom: 12px;
}

.section-navy .kicker { color: var(--ember-light); }

.lead { font-size: 1.12rem; color: var(--grey); max-width: 720px; }
.section-navy .lead { color: #c6d2e0; }

.muted { color: var(--grey); }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 13px 26px;
  border-radius: 50px;
  font-weight: 700;
  font-size: 0.95rem;
  border: 2px solid transparent;
  cursor: pointer;
  transition: all .2s;
}
.btn-ember { background: var(--ember); color: #fff; }
.btn-ember:hover { background: var(--ember-light); color: #fff; }
.btn-outline { border-color: var(--navy); color: var(--navy); background: transparent; }
.btn-outline:hover { background: var(--navy); color: #fff; }
.btn-outline-light { border-color: #fff; color: #fff; background: transparent; }
.btn-outline-light:hover { background: #fff; color: var(--navy); }
.btn-white { background: #fff; color: var(--navy); }
.btn-white:hover { background: var(--cream); color: var(--navy); }
.btn-sm { padding: 9px 18px; font-size: 0.85rem; }

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.header-inner { display: flex; align-items: center; gap: 28px; height: 74px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; font-size: 1.1rem; color: var(--navy); letter-spacing: 0.02em; }
.brand:hover { color: var(--navy); }
.brand-mark {
  width: 38px; height: 38px; border-radius: 10px;
  background: linear-gradient(135deg, var(--ember), var(--ember-light));
  display: grid; place-items: center; color: #fff; font-size: 1.2rem; font-weight: 800;
}
.brand small { display: block; font-size: 0.62rem; font-weight: 600; letter-spacing: 0.18em; color: var(--grey); text-transform: uppercase; }

.main-nav { display: flex; gap: 4px; margin-left: auto; }
.main-nav a {
  color: var(--ink); font-weight: 600; font-size: 0.92rem;
  padding: 8px 13px; border-radius: 8px;
}
.main-nav a:hover, .main-nav a.active { color: var(--ember); background: var(--ember-soft); }

.nav-toggle { display: none; background: none; border: none; font-size: 1.6rem; color: var(--navy); cursor: pointer; }

.header-cta { margin-left: 8px; white-space: nowrap; }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  background: linear-gradient(120deg, var(--navy) 0%, var(--navy-2) 60%, var(--navy-3) 100%);
  color: #fff;
  overflow: hidden;
}
.hero-grid { display: grid; grid-template-columns: 1.05fr 0.95fr; gap: 48px; align-items: center; padding: 88px 0; }
.hero h1 { color: #fff; margin: 10px 0 18px; }
.hero .lead { color: #c6d2e0; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 30px; }
.hero-stats { display: flex; flex-wrap: wrap; gap: 34px; margin-top: 44px; padding-top: 30px; border-top: 1px solid rgba(255,255,255,0.16); }
.hero-stats .stat b { display: block; font-size: 1.7rem; color: #fff; }
.hero-stats .stat span { font-size: 0.85rem; color: #a9b9cc; }
.hero-media { position: relative; }
.hero-media img { border-radius: 20px; box-shadow: var(--shadow-lg); }
.hero-badge {
  position: absolute; left: -18px; bottom: 26px;
  background: #fff; color: var(--navy); border-radius: 14px; padding: 14px 20px;
  box-shadow: var(--shadow-lg); display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 0.9rem;
}
.hero-badge .dot { width: 10px; height: 10px; border-radius: 50%; background: #2bb673; box-shadow: 0 0 0 4px rgba(43,182,115,.2); }

/* ---------- Cards / grids ---------- */
.grid { display: grid; gap: 26px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

.card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 28px; transition: transform .25s, box-shadow .25s;
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }

.icon-chip {
  width: 52px; height: 52px; border-radius: 13px; display: grid; place-items: center;
  background: var(--ember-soft); color: var(--ember); font-size: 1.5rem; margin-bottom: 16px;
}

/* ---------- Product cards ---------- */
.product-card { overflow: hidden; padding: 0; }
.product-card .thumb { position: relative; aspect-ratio: 4 / 3; overflow: hidden; background: var(--cream); }
.product-card .thumb img { width: 100%; height: 100%; object-fit: cover; transition: transform .4s; }
.product-card:hover .thumb img { transform: scale(1.05); }
.product-card .body { padding: 22px 24px 26px; }
.product-card .body h3 { margin-bottom: 8px; }
.product-card .tag-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0 14px; }
.tag {
  font-size: 0.74rem; font-weight: 700; letter-spacing: 0.03em;
  background: var(--cream); color: var(--navy); border: 1px solid var(--line);
  padding: 4px 10px; border-radius: 20px;
}
.tag-ember { background: var(--ember-soft); color: var(--ember); border-color: transparent; }

/* ---------- Feature list ---------- */
.check-list { list-style: none; margin: 16px 0 0; }
.check-list li { padding-left: 30px; position: relative; margin-bottom: 10px; }
.check-list li::before {
  content: "✓";
  position: absolute; left: 0; top: 0;
  width: 20px; height: 20px; border-radius: 50%;
  background: var(--ember-soft); color: var(--ember);
  font-size: 0.72rem; font-weight: 800; display: grid; place-items: center;
}

/* ---------- Steps ---------- */
.steps { counter-reset: step; display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.step { position: relative; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 30px 24px 24px; }
.step::before {
  counter-increment: step; content: "0" counter(step);
  position: absolute; top: -16px; left: 24px;
  background: var(--navy); color: #fff; font-weight: 800; font-size: 0.9rem;
  padding: 6px 14px; border-radius: 20px;
}
.step h3 { margin: 8px 0 8px; }
.step p { font-size: 0.92rem; color: var(--grey); }

/* ---------- Quote / CTA band ---------- */
.cta-band {
  background: linear-gradient(120deg, var(--ember), var(--ember-light));
  border-radius: 22px; padding: 52px 48px; color: #fff;
  display: flex; align-items: center; justify-content: space-between; gap: 30px; flex-wrap: wrap;
}
.cta-band h2 { color: #fff; margin-bottom: 6px; }
.cta-band p { color: rgba(255,255,255,0.92); max-width: 560px; }

/* ---------- Table ---------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius); background: #fff; }
table { width: 100%; border-collapse: collapse; font-size: 0.93rem; min-width: 640px; }
th, td { padding: 13px 18px; text-align: left; border-bottom: 1px solid var(--line); }
th { background: var(--cream); color: var(--navy); font-size: 0.82rem; letter-spacing: 0.05em; text-transform: uppercase; }
tr:last-child td { border-bottom: none; }
tbody tr:hover { background: #fdfaf6; }

/* ---------- FAQ ---------- */
.faq-item { border: 1px solid var(--line); border-radius: var(--radius); background: #fff; margin-bottom: 14px; overflow: hidden; }
.faq-item summary {
  cursor: pointer; list-style: none; padding: 20px 24px; font-weight: 700; color: var(--navy);
  display: flex; justify-content: space-between; align-items: center; gap: 16px;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after { content: "+"; font-size: 1.4rem; color: var(--ember); font-weight: 400; }
.faq-item[open] summary::after { content: "−"; }
.faq-item .faq-body { padding: 0 24px 20px; color: var(--grey); }

/* ---------- Breadcrumb ---------- */
.breadcrumb { font-size: 0.85rem; color: var(--grey); padding: 22px 0 0; }
.breadcrumb a { color: var(--grey); }
.breadcrumb a:hover { color: var(--ember); }
.breadcrumb span.sep { margin: 0 8px; color: var(--grey-light); }

/* ---------- Page hero (inner) ---------- */
.page-hero { background: linear-gradient(120deg, var(--navy), var(--navy-2)); color: #fff; padding: 64px 0; }
.page-hero h1 { color: #fff; margin-bottom: 10px; }
.page-hero .lead { color: #c6d2e0; }

/* ---------- Blog ---------- */
.post-card { overflow: hidden; }
.post-card .thumb { aspect-ratio: 16 / 9; background: var(--cream); overflow: hidden; }
.post-card .thumb img { width: 100%; height: 100%; object-fit: cover; }
.post-card .body { padding: 24px; }
.post-meta { font-size: 0.82rem; color: var(--grey); margin-bottom: 8px; }
.article-body { max-width: 780px; }
.article-body h2 { margin: 40px 0 14px; font-size: 1.6rem; }
.article-body h3 { margin: 28px 0 10px; }
.article-body p { margin-bottom: 18px; color: #3d4a58; }
.article-body ul, .article-body ol { margin: 0 0 18px 22px; color: #3d4a58; }
.article-body li { margin-bottom: 8px; }

/* ---------- Contact ---------- */
.contact-grid { display: grid; grid-template-columns: 1fr 1.1fr; gap: 40px; align-items: start; }
.info-item { display: flex; gap: 16px; padding: 18px 0; border-bottom: 1px solid var(--line); }
.info-item .icon-chip { margin: 0; flex-shrink: 0; width: 46px; height: 46px; font-size: 1.2rem; }
.form-card { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 32px; box-shadow: var(--shadow); }
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.form-group { display: flex; flex-direction: column; gap: 6px; }
.form-group.full { grid-column: 1 / -1; }
label { font-size: 0.85rem; font-weight: 700; color: var(--navy); }
input, select, textarea {
  font-family: var(--font); font-size: 0.95rem; color: var(--ink);
  border: 1px solid var(--line); border-radius: var(--radius-sm);
  padding: 12px 14px; background: #fff; width: 100%;
}
input:focus, select:focus, textarea:focus { outline: 2px solid var(--ember-light); border-color: transparent; }
textarea { resize: vertical; min-height: 120px; }

/* ---------- Footer ---------- */
.site-footer { background: var(--navy); color: #b9c6d6; padding: 64px 0 0; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1.2fr; gap: 40px; padding-bottom: 48px; }
.site-footer h4 { color: #fff; margin-bottom: 16px; font-size: 0.95rem; letter-spacing: 0.06em; text-transform: uppercase; }
.site-footer a { color: #b9c6d6; display: block; margin-bottom: 9px; font-size: 0.92rem; }
.site-footer a:hover { color: var(--ember-light); }
.site-footer .brand { color: #fff; margin-bottom: 14px; }
.site-footer p { font-size: 0.9rem; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,0.12); padding: 22px 0; display: flex; justify-content: space-between; gap: 14px; flex-wrap: wrap; font-size: 0.83rem; }

/* ---------- Utility ---------- */
.center { text-align: center; }
.mt-16 { margin-top: 16px; }
.mt-24 { margin-top: 24px; }
.mt-40 { margin-top: 40px; }
.mb-24 { margin-bottom: 24px; }
.reveal { opacity: 0; transform: translateY(22px); transition: opacity .6s, transform .6s; }
.reveal.in { opacity: 1; transform: none; }

.back-top {
  position: fixed; right: 22px; bottom: 22px; z-index: 90;
  width: 44px; height: 44px; border-radius: 50%; border: none; cursor: pointer;
  background: var(--navy); color: #fff; font-size: 1.1rem; box-shadow: var(--shadow);
  opacity: 0; pointer-events: none; transition: opacity .3s;
}
.back-top.show { opacity: 1; pointer-events: auto; }

/* ---------- Responsive ---------- */
@media (max-width: 980px) {
  .hero-grid { grid-template-columns: 1fr; padding: 60px 0; }
  .hero-media { order: -1; }
  .hero-badge { left: 12px; }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: repeat(2, 1fr); gap: 30px 20px; }
  .contact-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }

  .main-nav {
    position: fixed; inset: 74px 0 auto 0; background: #fff; flex-direction: column;
    padding: 16px 24px 24px; gap: 2px; border-bottom: 1px solid var(--line);
    transform: translateY(-120%); transition: transform .3s; box-shadow: var(--shadow-lg);
  }
  .main-nav.open { transform: none; }
  .main-nav a { padding: 13px 10px; font-size: 1rem; }
  .nav-toggle { display: block; margin-left: auto; }
  .header-cta { display: none; }
}

@media (max-width: 620px) {
  .section { padding: 60px 0; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .steps { grid-template-columns: 1fr; }
  .form-grid { grid-template-columns: 1fr; }
  .cta-band { padding: 36px 26px; }
  .hero-stats { gap: 20px; }
  .footer-grid { grid-template-columns: 1fr; }
}