/* ============================================
   Jinsutong · Premium Engineering Plastics Site
   Design: Deep navy + gold accent · 大气
   ============================================ */

:root {
  --color-primary: #0a2540;
  --color-primary-dark: #061b2e;
  --color-primary-light: #0c4a6e;
  --color-accent: #c9a961;
  --color-accent-light: #d4b676;
  --color-accent-dark: #a88a4a;
  --color-text: #1f2937;
  --color-text-soft: #4b5563;
  --color-muted: #6b7280;
  --color-muted-light: #9ca3af;
  --color-bg: #ffffff;
  --color-bg-alt: #f8fafc;
  --color-bg-dark: #0a2540;
  --color-border: #e5e7eb;
  --color-border-strong: #cbd5e1;
  --color-gold-soft: rgba(201, 169, 97, 0.12);
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 16px;
  --shadow-sm: 0 1px 2px rgba(10, 37, 64, 0.06);
  --shadow-md: 0 4px 12px rgba(10, 37, 64, 0.08);
  --shadow-lg: 0 12px 40px rgba(10, 37, 64, 0.10);
  --shadow-xl: 0 24px 60px rgba(10, 37, 64, 0.16);
  --container-max: 1240px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: var(--color-primary-light); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--color-accent); }

img, svg { display: block; max-width: 100%; }
.mono { font-family: "SF Mono", Menlo, Consolas, "Courier New", monospace; font-size: 0.92em; letter-spacing: 0.02em; }

.container { max-width: var(--container-max); margin: 0 auto; padding: 0 32px; }

/* ============================================
   Header / Navigation
   ============================================ */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: transparent;
  transition: background var(--transition), box-shadow var(--transition), padding var(--transition);
  padding: 18px 0;
}
.site-header.scrolled {
  background: rgba(255, 255, 255, 0.97);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  box-shadow: var(--shadow-sm);
  padding: 12px 0;
}
.nav {
  display: flex; align-items: center; gap: 40px;
}
.brand {
  display: flex; align-items: center; gap: 12px;
  color: #fff; font-weight: 700;
  transition: color var(--transition);
}
.site-header.scrolled .brand { color: var(--color-primary); }
.brand-mark {
  display: inline-flex; align-items: center; justify-content: center;
  width: 38px; height: 38px;
  background: var(--color-accent);
  color: var(--color-primary-dark);
  font-family: "Georgia", "Times New Roman", serif;
  font-size: 18px; font-weight: 700; font-style: italic;
  border-radius: var(--radius-sm);
  letter-spacing: -0.02em;
}
.brand-name {
  font-size: 18px; font-weight: 700; letter-spacing: 0.02em;
  display: flex; flex-direction: column; line-height: 1.1;
}
.brand-sub { font-size: 11px; font-weight: 500; color: var(--color-accent); letter-spacing: 0.05em; }
.site-header.scrolled .brand-sub { color: var(--color-accent-dark); }

.nav-links { display: flex; gap: 32px; flex: 1; margin-left: 24px; }
.nav-links a {
  color: rgba(255, 255, 255, 0.92); font-size: 15px; font-weight: 500;
  position: relative; padding: 6px 0;
  transition: color var(--transition);
}
.nav-links a::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: 0;
  height: 2px; background: var(--color-accent);
  transform: scaleX(0); transform-origin: center;
  transition: transform var(--transition);
}
.nav-links a:hover::after, .nav-links a.active::after { transform: scaleX(1); }
.site-header.scrolled .nav-links a { color: var(--color-text-soft); }
.site-header.scrolled .nav-links a:hover { color: var(--color-primary); }

.nav-meta { display: flex; align-items: center; gap: 20px; }
.lang-switch {
  display: flex; align-items: center; gap: 6px;
  font-size: 13px; font-weight: 600; letter-spacing: 0.05em;
}
.lang-switch a { color: rgba(255, 255, 255, 0.7); padding: 4px 6px; }
.lang-switch a.lang-active { color: var(--color-accent); }
.lang-switch .lang-sep { color: rgba(255, 255, 255, 0.3); }
.site-header.scrolled .lang-switch a { color: var(--color-muted); }
.site-header.scrolled .lang-switch a.lang-active { color: var(--color-accent-dark); }
.site-header.scrolled .lang-switch .lang-sep { color: var(--color-border-strong); }
.site-header.scrolled .lang-switch a:hover, .lang-switch a:hover { color: var(--color-accent); }

.nav-cta {
  display: inline-flex; align-items: center;
  padding: 10px 20px;
  background: var(--color-accent);
  color: var(--color-primary-dark) !important;
  font-size: 14px; font-weight: 700; letter-spacing: 0.02em;
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}
.nav-cta:hover { background: var(--color-accent-light); transform: translateY(-1px); box-shadow: 0 4px 12px rgba(201, 169, 97, 0.4); }

/* ============================================
   Hero
   ============================================ */
.hero {
  position: relative;
  min-height: 92vh;
  display: flex; align-items: center;
  padding: 140px 0 100px;
  color: #fff;
  overflow: hidden;
}
.hero-bg { position: absolute; inset: 0; z-index: 0; }
.hero-pattern { width: 100%; height: 100%; }
.hero-inner { position: relative; z-index: 1; max-width: 920px; }
.eyebrow {
  display: inline-block;
  font-size: 12px; font-weight: 700;
  letter-spacing: 0.18em; text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 24px;
  position: relative; padding-left: 48px;
}
.eyebrow::before {
  content: ""; position: absolute; left: 0; top: 50%;
  width: 36px; height: 1px; background: var(--color-accent);
}
.hero-title {
  font-size: clamp(40px, 5.6vw, 68px);
  line-height: 1.12; font-weight: 800;
  letter-spacing: -0.025em;
  margin-bottom: 28px;
  color: #fff;
}
.hero-title .accent {
  background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-light) 100%);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
  font-style: italic; font-weight: 700;
}
.hero-tagline {
  font-size: clamp(16px, 1.5vw, 19px);
  line-height: 1.65; color: rgba(255, 255, 255, 0.85);
  max-width: 720px; margin-bottom: 44px;
  font-weight: 400;
}
.hero-tagline strong { color: var(--color-accent); font-weight: 700; }
.hero-cta { display: flex; gap: 16px; flex-wrap: wrap; margin-bottom: 80px; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 16px 32px;
  font-size: 15px; font-weight: 700; letter-spacing: 0.02em;
  border-radius: var(--radius-sm);
  transition: all var(--transition);
  cursor: pointer; border: 2px solid transparent;
}
.btn-primary { background: var(--color-accent); color: var(--color-primary-dark); }
.btn-primary:hover { background: var(--color-accent-light); color: var(--color-primary-dark); transform: translateY(-2px); box-shadow: 0 8px 24px rgba(201, 169, 97, 0.4); }
.btn-ghost { background: transparent; color: #fff; border-color: rgba(255, 255, 255, 0.3); }
.btn-ghost:hover { background: rgba(255, 255, 255, 0.08); border-color: var(--color-accent); color: var(--color-accent); transform: translateY(-2px); }

.hero-stats {
  display: flex; align-items: center; gap: 0;
  padding-top: 36px;
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  max-width: 720px;
}
.stat { padding: 0 32px; }
.stat:first-child { padding-left: 0; }
.stat .num {
  font-family: "Georgia", "Times New Roman", serif;
  font-size: 44px; font-weight: 700;
  color: var(--color-accent);
  line-height: 1; margin-bottom: 8px;
  letter-spacing: -0.02em;
}
.stat .label {
  font-size: 12px; font-weight: 600; letter-spacing: 0.08em;
  color: rgba(255, 255, 255, 0.7);
  text-transform: uppercase;
}
.stat-divider { width: 1px; height: 48px; background: rgba(255, 255, 255, 0.12); }

/* ============================================
   Sections (shared)
   ============================================ */
.section { padding: 120px 0; }
.section-about { background: var(--color-bg); }
.section-products { background: var(--color-bg-alt); }
.section-contact { background: var(--color-bg); }

.section-head { max-width: 760px; margin: 0 auto 64px; text-align: center; }
.section-head .eyebrow { padding-left: 0; }
.section-head .eyebrow::before { display: none; }
.section-title {
  font-size: clamp(32px, 3.6vw, 48px);
  line-height: 1.18; font-weight: 800;
  letter-spacing: -0.022em;
  color: var(--color-primary);
  margin: 18px auto 20px;
  position: relative; display: inline-block;
}
.section-title::after {
  content: ""; display: block;
  width: 56px; height: 3px; background: var(--color-accent);
  margin: 24px auto 0;
}
.section-lead {
  font-size: 17px; line-height: 1.7;
  color: var(--color-text-soft);
  max-width: 640px; margin: 0 auto;
}

/* ============================================
   About Grid
   ============================================ */
.about-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}
.about-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-top: 3px solid var(--color-accent);
  border-radius: var(--radius-md);
  padding: 36px 28px;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}
.about-card::before {
  content: ""; position: absolute; left: 0; top: 0;
  width: 0; height: 3px; background: var(--color-accent);
  transition: width var(--transition-slow);
}
.about-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: transparent; }
.about-card:hover::before { width: 100%; }
.about-icon { font-size: 32px; margin-bottom: 16px; }
.about-card h3 {
  font-size: 13px; font-weight: 700;
  letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--color-accent-dark);
  margin-bottom: 12px;
}
.about-card p { font-size: 15px; line-height: 1.6; color: var(--color-text); margin-bottom: 4px; }
.about-card .muted { font-size: 13px; color: var(--color-muted); margin-top: 6px; }
.about-card .muted-strong { font-weight: 600; color: var(--color-primary); }

/* ============================================
   Products Grid
   ============================================ */
.products-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
  margin-bottom: 80px;
}
.product-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 32px 28px;
  transition: all var(--transition);
  display: flex; gap: 20px;
  position: relative; overflow: hidden;
}
.product-card::after {
  content: ""; position: absolute; left: 0; bottom: 0;
  width: 100%; height: 3px;
  background: linear-gradient(90deg, var(--color-accent) 0%, var(--color-accent-light) 100%);
  transform: scaleX(0); transform-origin: left;
  transition: transform var(--transition-slow);
}
.product-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-xl); border-color: var(--color-accent); }
.product-card:hover::after { transform: scaleX(1); }
.product-num {
  font-family: "Georgia", "Times New Roman", serif;
  font-size: 36px; font-weight: 700; font-style: italic;
  color: var(--color-accent); line-height: 1;
  letter-spacing: -0.02em;
  flex-shrink: 0;
}
.product-body { flex: 1; }
.product-name {
  font-size: 28px; font-weight: 800;
  color: var(--color-primary);
  letter-spacing: -0.02em;
  margin-bottom: 4px;
}
.product-full {
  font-size: 13px; font-weight: 600;
  color: var(--color-accent-dark);
  letter-spacing: 0.04em;
  margin-bottom: 14px;
  text-transform: uppercase;
}
.product-desc {
  font-size: 14px; line-height: 1.65;
  color: var(--color-text-soft);
}

.products-secondary {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 48px 40px;
  text-align: center;
}
.secondary-title {
  font-size: 24px; font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}
.secondary-lead {
  font-size: 15px; color: var(--color-text-soft);
  margin-bottom: 32px; max-width: 600px; margin-left: auto; margin-right: auto;
}
.chips { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; }
.chip {
  display: inline-block;
  padding: 8px 16px;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  color: var(--color-primary);
  font-size: 13px; font-weight: 600;
  border-radius: 100px;
  letter-spacing: 0.02em;
  transition: all var(--transition);
  cursor: default;
}
.chip:hover { background: var(--color-accent); color: var(--color-primary-dark); border-color: var(--color-accent); transform: translateY(-2px); }

/* ============================================
   Contact
   ============================================ */
.contact-card {
  max-width: 820px; margin: 0 auto;
  background: var(--color-bg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  padding: 16px;
  border-top: 4px solid var(--color-accent);
}
.contact-row {
  display: grid; grid-template-columns: 160px 1fr;
  gap: 24px; align-items: center;
  padding: 24px 28px;
  border-bottom: 1px solid var(--color-border);
  transition: background var(--transition);
}
.contact-row:hover { background: var(--color-bg-alt); }
.contact-row:last-child { border-bottom: none; }
.contact-label {
  font-size: 12px; font-weight: 700;
  letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--color-accent-dark);
}
.contact-value { display: flex; flex-direction: column; gap: 4px; }
.contact-value strong { font-size: 17px; color: var(--color-text); font-weight: 600; }
.contact-value .muted { font-size: 13px; color: var(--color-muted); }
.contact-value a { font-size: 17px; color: var(--color-primary-light); font-weight: 600; }
.contact-value a:hover { color: var(--color-accent-dark); }
.contact-value span { font-size: 17px; color: var(--color-text); font-weight: 500; }

/* ============================================
   Footer
   ============================================ */
.site-footer {
  background: var(--color-bg-dark);
  color: rgba(255, 255, 255, 0.7);
  padding: 80px 0 0;
}
.footer-inner {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1.2fr;
  gap: 48px;
  padding-bottom: 60px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}
.footer-col h4 {
  font-size: 12px; font-weight: 700;
  letter-spacing: 0.15em; text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 20px;
}
.footer-col ul { list-style: none; }
.footer-col li {
  font-size: 14px; line-height: 1.9;
  color: rgba(255, 255, 255, 0.7);
}
.footer-col li a { color: rgba(255, 255, 255, 0.85); }
.footer-col li a:hover { color: var(--color-accent); }
.footer-col li.mono { color: var(--color-accent-light); font-size: 12px; }
.footer-brand { display: flex; align-items: center; gap: 12px; margin-bottom: 16px; color: #fff; }
.footer-brand .brand-mark { width: 36px; height: 36px; font-size: 16px; }
.footer-brand .brand-name { font-size: 18px; font-weight: 700; }
.footer-tagline {
  font-size: 14px; color: rgba(255, 255, 255, 0.6);
  letter-spacing: 0.02em;
}
.footer-bottom {
  padding: 28px 0;
  background: var(--color-primary-dark);
}
.footer-bottom .container {
  display: flex; justify-content: space-between; align-items: center;
  flex-wrap: wrap; gap: 12px;
  font-size: 12px;
}
.footer-bottom p { color: rgba(255, 255, 255, 0.55); }
.footer-bottom .muted-small { font-size: 11px; color: rgba(255, 255, 255, 0.4); }

/* ============================================
   Applications
   ============================================ */
.applications-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.application-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  text-align: center;
  transition: all var(--transition);
}
.application-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-accent);
}
.app-icon {
  font-size: 36px;
  margin-bottom: 16px;
  display: inline-block;
  line-height: 1;
}
.application-card h3 {
  font-size: 18px;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}
.application-card p {
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-text-soft);
}

/* ============================================
   Why Choose Us
   ============================================ */
.why-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}
.why-card {
  background: var(--color-bg-alt);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  position: relative;
  transition: all var(--transition);
  border-top: 3px solid transparent;
}
.why-card:hover {
  background: var(--color-bg);
  border-top-color: var(--color-accent);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}
.why-num {
  font-family: "Georgia", "Times New Roman", serif;
  font-size: 24px;
  font-weight: 700;
  font-style: italic;
  color: var(--color-accent);
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}
.why-card h3 {
  font-size: 17px;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 10px;
  letter-spacing: -0.01em;
}
.why-card p {
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-text-soft);
}

/* ============================================
   FAQ
   ============================================ */
.faq-list {
  max-width: 860px;
  margin: 0 auto;
}
.faq-item {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  margin-bottom: 12px;
  overflow: hidden;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.faq-item:hover { border-color: var(--color-border-strong); }
.faq-item[open] {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-sm);
}
.faq-question {
  padding: 20px 56px 20px 24px;
  font-size: 16px;
  font-weight: 600;
  color: var(--color-primary);
  cursor: pointer;
  list-style: none;
  position: relative;
  transition: color var(--transition);
}
.faq-question::-webkit-details-marker { display: none; }
.faq-question::marker { content: ""; }
.faq-question::after {
  content: "+";
  position: absolute;
  right: 24px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 22px;
  font-weight: 400;
  color: var(--color-accent);
  transition: transform var(--transition);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1;
}
.faq-item[open] .faq-question::after {
  transform: translateY(-50%) rotate(45deg);
}
.faq-question:hover { color: var(--color-accent-dark); }
.faq-answer {
  padding: 0 24px 20px;
  font-size: 15px;
  line-height: 1.7;
  color: var(--color-text-soft);
}
.faq-answer p { margin: 0; }
.faq-answer a { color: var(--color-primary-light); text-decoration: underline; }
.faq-answer a:hover { color: var(--color-accent-dark); }

/* ============================================
   Grades Page
   ============================================ */
.page-hero {
  background: linear-gradient(135deg, #0a2540 0%, #0c4a6e 100%);
  color: #fff;
  padding: 140px 0 64px;
  position: relative;
  overflow: hidden;
}
.page-hero::before {
  content: "";
  position: absolute; inset: 0;
  background-image: radial-gradient(circle at 2px 2px, rgba(201,169,97,0.10) 1px, transparent 1px);
  background-size: 40px 40px;
  pointer-events: none;
}
.page-hero .container { position: relative; z-index: 1; }
.page-hero .eyebrow { color: var(--color-accent); }
.page-title {
  font-size: clamp(36px, 5vw, 56px);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.15;
  margin-bottom: 20px;
}
.page-lead {
  font-size: 17px;
  line-height: 1.65;
  color: rgba(255,255,255,0.85);
  max-width: 760px;
  margin-bottom: 32px;
}
.page-disclaimer {
  background: rgba(255,255,255,0.06);
  border-left: 3px solid var(--color-accent);
  border-radius: var(--radius-md);
  padding: 18px 22px;
  font-size: 14px;
  line-height: 1.7;
  color: rgba(255,255,255,0.92);
  max-width: 900px;
}
.page-disclaimer strong { color: var(--color-accent); }
.page-disclaimer a { color: var(--color-accent-light); text-decoration: underline; }

.grades-toc {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 24px 28px;
  margin-bottom: 48px;
}
.toc-label {
  font-size: 12px; font-weight: 700;
  letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--color-accent-dark);
  margin-bottom: 14px;
}
.toc-chips { display: flex; flex-wrap: wrap; gap: 8px; }
.toc-chips .chip {
  font-size: 12px;
  padding: 6px 12px;
  text-decoration: none;
}
.toc-chips .chip:hover { background: var(--color-accent); color: var(--color-primary-dark); border-color: var(--color-accent); transform: translateY(-1px); }

/* Domestic-alternative marker badge (used on grade tables to flag [国产替代 · 库存待询]) */
.tag-family { display: inline-block; margin-left: 6px; padding: 2px 8px; font-size: 11px; font-weight: 600; line-height: 1.4; color: #1e3a5f; background: #e8f0fe; border: 1px solid #93b4e8; border-radius: 999px; vertical-align: middle; white-space: nowrap; letter-spacing: 0.01em; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif; }
.tag-discontinued { display: inline-block; margin-left: 6px; padding: 2px 8px; font-size: 11px; font-weight: 600; line-height: 1.4; color: #374151; background: #f3f4f6; border: 1px solid #d1d5db; border-radius: 999px; vertical-align: middle; white-space: nowrap; letter-spacing: 0.01em; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif; }
.tag-domestic {
  display: inline-block;
  margin-left: 6px;
  padding: 2px 8px;
  font-size: 11px;
  font-weight: 600;
  line-height: 1.4;
  color: #92400e;
  background: #fef3c7;
  border: 1px solid #fcd34d;
  border-radius: 999px;
  vertical-align: middle;
  white-space: nowrap;
  letter-spacing: 0;
  letter-spacing: 0.01em;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}
.tag-domestic::before {
  content: "●";
  color: #d97706;
  font-size: 10px;
  margin-right: 4px;
  vertical-align: middle;
}

.grades-group-title {
  font-size: 28px; font-weight: 800;
  color: var(--color-primary);
  letter-spacing: -0.02em;
  margin: 56px 0 28px;
  padding-bottom: 14px;
  border-bottom: 3px solid var(--color-accent);
  display: inline-block;
}

.grade-category {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 28px 32px;
  margin-bottom: 20px;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.grade-category:hover { border-color: var(--color-border-strong); box-shadow: var(--shadow-sm); }
.grade-category-head { margin-bottom: 18px; }
.grade-category-head h3 {
  font-size: 22px; font-weight: 800;
  color: var(--color-primary);
  letter-spacing: -0.01em;
  margin-bottom: 6px;
}
.grade-meta {
  font-size: 14px;
  color: var(--color-text-soft);
  line-height: 1.6;
}

.grade-table-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
}
.grade-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
  background: var(--color-bg);
  min-width: 640px;
}
.grade-table thead {
  background: var(--color-bg-alt);
}
.grade-table th {
  text-align: left;
  padding: 12px 16px;
  font-size: 11px; font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent-dark);
  border-bottom: 2px solid var(--color-border-strong);
}
.grade-table td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--color-border);
  color: var(--color-text);
  vertical-align: top;
}
.grade-table tbody tr:last-child td { border-bottom: none; }
.grade-table tbody tr:hover { background: var(--color-bg-alt); }
.grade-name {
  font-weight: 700;
  color: var(--color-primary);
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 13px;
}

.grade-cta {
  margin-top: 56px;
  background: linear-gradient(135deg, var(--color-bg-alt) 0%, #eef2f6 100%);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 48px 40px;
  text-align: center;
}
.grade-cta h3 {
  font-size: 24px; font-weight: 800;
  color: var(--color-primary);
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}
.grade-cta p {
  font-size: 15px; color: var(--color-text-soft);
  max-width: 600px;
  margin: 0 auto 28px;
  line-height: 1.7;
}
.cta-actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

/* ============================================
   Animations · Reveal on scroll
   ============================================ */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1), transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 900px) {
  .container { padding: 0 24px; }
  .nav-links { display: none; }
  .nav { gap: 16px; }
  .nav-meta { gap: 12px; margin-left: auto; }
  .nav-cta { padding: 8px 14px; font-size: 13px; }
  .hero { min-height: 80vh; padding: 120px 0 80px; }
  .hero-stats { flex-wrap: wrap; gap: 24px 0; }
  .stat { padding: 0 20px; }
  .stat-divider { display: none; }
  .section { padding: 80px 0; }
  .section-head { margin-bottom: 48px; }
  .product-card { padding: 24px 20px; }
  .products-secondary { padding: 32px 20px; }
  .contact-row { grid-template-columns: 1fr; gap: 8px; padding: 20px; }
  .contact-label { font-size: 11px; }
  .footer-inner { grid-template-columns: 1fr 1fr; gap: 32px; }
  .applications-grid { grid-template-columns: 1fr 1fr; }
  .why-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 600px) {
  .applications-grid { grid-template-columns: 1fr; }
  .why-grid { grid-template-columns: 1fr; }
  .faq-question { padding: 16px 52px 16px 20px; font-size: 15px; }
  .faq-question::after { right: 20px; }
  .faq-answer { padding: 0 20px 16px; font-size: 14px; }
  .page-hero { padding: 120px 0 48px; }
  .page-title { font-size: 32px; }
  .grade-category { padding: 20px 18px; }
  .grade-cta { padding: 32px 20px; }
  .hero-title { font-size: 36px; }
  .hero-cta { flex-direction: column; align-items: stretch; }
  .btn { justify-content: center; }
  .footer-inner { grid-template-columns: 1fr; }
  .footer-bottom .container { flex-direction: column; text-align: center; }
}

/* ============================================
   Print
   ============================================ */
@media print {
  .site-header, .site-footer, .hero-cta, .nav-meta { display: none; }
  .hero { min-height: auto; padding: 40px 0; background: #fff; color: #000; }
  .hero-title { color: #000; }
}

/* ============================================
   Handbook Section (index.html)
   ============================================ */
.section-handbooks { background: var(--color-bg-alt); border-top: 1px solid var(--color-border); }
.handbooks-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; margin-top: 24px; }
@media (max-width: 720px) { .handbooks-grid { grid-template-columns: 1fr; } }
.handbook-card { background: var(--color-bg); border: 1px solid var(--color-border); border-left: 4px solid var(--color-accent); border-radius: var(--radius-md); padding: 24px 26px; display: flex; flex-direction: column; gap: 10px; }
.handbook-card h3 { color: var(--color-primary); font-size: 18px; margin: 0; }
.handbook-card p { color: var(--color-text-soft); font-size: 14px; margin: 0; line-height: 1.55; flex: 1; }
.handbook-card .btn-primary { align-self: flex-start; margin-top: 4px; }
.handbook-icon { font-size: 28px; line-height: 1; }
.handbooks-footnote { margin-top: 24px; text-align: center; color: var(--color-text-soft); font-size: 14px; }
.handbooks-footnote a { color: var(--color-accent-dark); font-weight: 600; text-decoration: none; border-bottom: 1px dashed var(--color-accent); }
.handbooks-footnote a:hover { color: var(--color-primary); border-bottom-color: var(--color-primary); }

/* ============================================
   Per-grade PDF link (grades.html tables)
   ============================================ */
.grade-pdf { white-space: nowrap; }
.grade-pdf a { display: inline-block; padding: 3px 9px; background: var(--color-gold-soft); color: var(--color-accent-dark); border: 1px solid var(--color-accent); border-radius: var(--radius-sm); font-size: 11px; font-weight: 600; text-decoration: none; transition: all 0.15s ease; }
.grade-pdf a:hover { background: var(--color-accent); color: #fff; }
.grade-table th:last-child, .grade-table td.grade-pdf { width: 1%; }

/* ============================================
   Product page resource linkbar
   ============================================ */
.reso-linkbar { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; margin: 36px auto 24px; max-width: 800px; padding: 16px 20px; background: linear-gradient(135deg, var(--color-gold-soft) 0%, rgba(201,169,97,0.04) 100%); border: 1px solid var(--color-accent); border-radius: var(--radius-md); }
.reso-link { display: inline-block; padding: 8px 16px; font-size: 13px; font-weight: 600; text-decoration: none; border-radius: var(--radius-sm); transition: all 0.15s ease; }
.reso-link.reso-grades { background: var(--color-primary); color: #fff; }
.reso-link.reso-grades:hover { background: var(--color-primary-dark); }
.reso-link.reso-hb-en { background: #fff; color: var(--color-primary); border: 1px solid var(--color-primary); }
.reso-link.reso-hb-en:hover { background: var(--color-primary); color: #fff; }
.reso-link.reso-hb-zh { background: #fff; color: var(--color-accent-dark); border: 1px solid var(--color-accent); }
.reso-link.reso-hb-zh:hover { background: var(--color-accent); color: #fff; }
@media (max-width: 600px) { .reso-linkbar { flex-direction: column; align-items: stretch; } .reso-link { text-align: center; } }

/* ============================================
   Grade catalog filter (client-side search)
   ============================================ */
.grade-filter {
  margin: 0 0 28px;
  padding: 18px 20px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}
.grade-filter-bar { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; }
.grade-filter-label {
  font-size: 11px; font-weight: 700; letter-spacing: 0.09em; text-transform: uppercase;
  color: var(--color-text-soft); white-space: nowrap;
}
.grade-filter-input {
  flex: 1 1 320px; min-width: 230px;
  padding: 10px 14px;
  font-size: 15px; font-family: inherit;
  color: var(--color-text);
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-md);
  outline: none;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.grade-filter-input:focus { border-color: var(--color-accent); box-shadow: 0 0 0 3px var(--color-gold-soft); }
.grade-filter-count {
  font-size: 13px; font-weight: 600; color: var(--color-text-soft);
  white-space: nowrap; font-variant-numeric: tabular-nums;
}
.grade-filter-reset {
  padding: 9px 16px; font-size: 13px; font-weight: 600; font-family: inherit;
  color: var(--color-primary); background: transparent;
  border: 1px solid var(--color-border-strong); border-radius: var(--radius-md);
  cursor: pointer; transition: all 0.15s ease;
}
.grade-filter-reset:hover { background: var(--color-accent); border-color: var(--color-accent); color: #fff; }
.grade-filter-empty { margin: 12px 0 0; font-size: 14px; color: var(--color-text-soft); }
.grade-filter .is-filtered-out { display: none !important; }
@media (max-width: 720px) {
  .grade-filter { padding: 14px 16px; }
  .grade-filter-input { flex-basis: 100%; }
}
.tag-nostock { display: inline-block; margin-left: 6px; padding: 2px 8px; font-size: 11px; font-weight: 600; line-height: 1.4; color: #7c2d12; background: #fff1e6; border: 1px solid #f0b892; border-radius: 999px; vertical-align: middle; white-space: nowrap; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif; }
.tag-internal { display: inline-block; margin-left: 6px; padding: 2px 8px; font-size: 11px; font-weight: 600; line-height: 1.4; color: #3f3f46; background: #f4f4f5; border: 1px solid #d4d4d8; border-radius: 999px; vertical-align: middle; white-space: nowrap; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif; }
.tag-english { display: inline-block; margin-left: 6px; padding: 2px 8px; font-size: 11px; font-weight: 600; line-height: 1.4; color: #1e3a5f; background: #e8f0fe; border: 1px solid #93b4e8; border-radius: 999px; vertical-align: middle; white-space: nowrap; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif; }
.tag-refdoc { display: inline-block; margin-left: 6px; padding: 2px 8px; font-size: 11px; font-weight: 600; line-height: 1.4; color: #1e40af; background: #eff6ff; border: 1px solid #93c5fd; border-radius: 999px; vertical-align: middle; white-space: nowrap; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif; }
.product-brands { margin-top: 8px; font-size: 12px; line-height: 1.6; color: var(--color-text-soft); font-weight: 500; }
.product-brands::before { content: "Brands: "; color: var(--color-muted); font-weight: 600; }
body:lang(zh) .product-brands::before { content: "主要品牌："; }