/* ==========================================================================
   鼎天国际官网 style.css
   国际品牌与营销AI大模型平台 — 全站样式
   ========================================================================== */

:root {
  --navy-900: #071B33;
  --navy-800: #0A2647;
  --navy-700: #123A63;
  --navy-600: #1B4C7E;
  --teal-600: #146B64;
  --teal-500: #1E8A80;
  --teal-100: #E4F3F1;
  --gold-600: #B08A2E;
  --gold-500: #C9A24B;
  --gold-100: #F8EFD9;
  --bg: #F5F7FB;
  --surface: #FFFFFF;
  --surface-alt: #F0F3F9;
  --border: #E1E6F0;
  --border-strong: #C7D0E0;
  --text: #17202E;
  --text-soft: #47546A;
  --text-mute: #6C7890;
  --text-invert: #F3F6FC;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --shadow-sm: 0 1px 2px rgba(10, 38, 71, 0.06), 0 1px 1px rgba(10, 38, 71, 0.04);
  --shadow-md: 0 8px 24px rgba(10, 38, 71, 0.08);
  --shadow-lg: 0 20px 48px rgba(10, 38, 71, 0.14);
  --maxw: 1180px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img, svg { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul, ol { margin: 0; padding: 0; list-style: none; }
h1, h2, h3, h4, p { margin: 0; }
button { font-family: inherit; cursor: pointer; }
.container {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
}
.visually-hidden {
  position: absolute; width: 1px; height: 1px; overflow: hidden;
  clip: rect(0 0 0 0); white-space: nowrap;
}

/* ---------------- Top bar & Header ---------------- */
.topbar {
  background: var(--navy-900);
  color: var(--text-invert);
  font-size: 13px;
}
.topbar .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 6px;
  padding-bottom: 6px;
  gap: 12px;
  flex-wrap: wrap;
}
.topbar-tag { color: #B9C6DE; }
.topbar-brand { color: var(--gold-500); font-weight: 600; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255,255,255,0.94);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 76px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 20px;
  color: var(--navy-800);
}
.brand .brand-logo { width: 40px; height: 40px; }
.brand .brand-name-en {
  display: block;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.14em;
  color: var(--text-mute);
  text-transform: uppercase;
}

.main-nav { display: flex; align-items: center; gap: 4px; }
.main-nav a {
  padding: 10px 16px;
  font-size: 15px;
  font-weight: 500;
  color: var(--text-soft);
  border-radius: var(--radius-sm);
  transition: background 0.15s, color 0.15s;
}
.main-nav a:hover,
.main-nav a[aria-current="page"] {
  color: var(--navy-800);
  background: var(--surface-alt);
}
.main-nav a[aria-current="page"] { font-weight: 700; }

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  width: 42px;
  height: 42px;
  align-items: center;
  justify-content: center;
}
.nav-toggle span,
.nav-toggle span::before,
.nav-toggle span::after {
  content: "";
  display: block;
  width: 20px;
  height: 2px;
  background: var(--navy-800);
  position: relative;
  transition: transform 0.2s;
}
.nav-toggle span::before { position: absolute; top: -6px; }
.nav-toggle span::after { position: absolute; top: 6px; }

/* ---------------- Buttons ---------------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 600;
  border: 1px solid transparent;
  transition: transform 0.15s, box-shadow 0.15s, background 0.15s;
}
.btn-primary { background: var(--navy-800); color: #fff; }
.btn-primary:hover { background: var(--navy-700); box-shadow: var(--shadow-md); transform: translateY(-1px); }
.btn-gold { background: var(--gold-500); color: var(--navy-900); }
.btn-gold:hover { background: var(--gold-600); transform: translateY(-1px); }
.btn-outline { background: transparent; color: var(--navy-800); border-color: var(--border-strong); }
.btn-outline:hover { border-color: var(--navy-700); background: var(--surface-alt); }

/* ---------------- Hero ---------------- */
.hero {
  background: linear-gradient(160deg, var(--navy-900) 0%, var(--navy-800) 55%, var(--teal-600) 130%);
  color: var(--text-invert);
  padding: 64px 0 72px;
  position: relative;
  overflow: hidden;
}
.hero .container {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: center;
  position: relative;
  z-index: 1;
}
.hero-eyebrow {
  display: inline-block;
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--gold-500);
  background: rgba(201,162,75,0.14);
  border: 1px solid rgba(201,162,75,0.4);
  padding: 6px 14px;
  border-radius: 999px;
  margin-bottom: 18px;
}
.hero h1 {
  font-size: clamp(28px, 4vw, 42px);
  line-height: 1.35;
  font-weight: 800;
  margin-bottom: 18px;
}
.hero p.lead {
  font-size: 17px;
  color: #D7E1F2;
  max-width: 620px;
  margin-bottom: 28px;
}
.hero-actions { display: flex; gap: 14px; flex-wrap: wrap; margin-bottom: 30px; }
.hero-stats {
  display: flex;
  gap: 28px;
  flex-wrap: wrap;
  font-size: 13px;
  color: #A9BAD6;
}
.hero-stats strong { display: block; font-size: 20px; color: #fff; font-weight: 700; }
.hero-art { position: relative; }
.hero-art svg { width: 100%; height: auto; }
.page-hero {
  background: linear-gradient(160deg, var(--navy-900), var(--navy-700) 120%);
  color: var(--text-invert);
  padding: 52px 0 56px;
}
.page-hero .hero-eyebrow { margin-bottom: 14px; }
.page-hero h1 { font-size: clamp(26px, 3.6vw, 36px); font-weight: 800; margin-bottom: 14px; }
.page-hero p.lead { color: #D7E1F2; max-width: 760px; font-size: 16px; }

/* ---------------- Section scaffolding ---------------- */
.section { padding: 64px 0; }
.section-alt { background: var(--surface-alt); }
.section-head {
  max-width: 760px;
  margin: 0 auto 40px;
  text-align: center;
}
.section-head.left { text-align: left; margin-left: 0; }
.kicker {
  display: block;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--teal-600);
  margin-bottom: 10px;
}
.section h2 {
  font-size: clamp(22px, 3vw, 30px);
  font-weight: 800;
  color: var(--navy-800);
  margin-bottom: 12px;
}
.section .desc { color: var(--text-soft); font-size: 15.5px; }

/* ---------------- Value chain ---------------- */
.chain {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  align-items: center;
}
.chain-node {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 10px 18px;
  font-size: 13.5px;
  font-weight: 600;
  color: var(--navy-700);
  box-shadow: var(--shadow-sm);
}
.chain-arrow { color: var(--border-strong); font-size: 16px; }

/* ---------------- Cards & Grids ---------------- */
.grid { display: grid; gap: 24px; }
.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: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 26px;
  box-shadow: var(--shadow-sm);
}
.card h3 { font-size: 17px; color: var(--navy-800); margin-bottom: 10px; font-weight: 700; }
.card p { color: var(--text-soft); font-size: 14.5px; }
.icon-tile {
  width: 46px; height: 46px;
  border-radius: 12px;
  background: var(--teal-100);
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 14px;
}
.icon-tile svg { width: 26px; height: 26px; }

/* ---------------- Article system ---------------- */
.article-list { display: flex; flex-direction: column; gap: 40px; }
.article {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 34px;
  box-shadow: var(--shadow-sm);
}
.article-meta {
  display: flex;
  gap: 14px;
  align-items: center;
  font-size: 13px;
  color: var(--text-mute);
  margin-bottom: 14px;
  flex-wrap: wrap;
}
.article-meta .tag {
  background: var(--gold-100);
  color: var(--gold-600);
  padding: 3px 10px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 12px;
}
.article h3, .article h2.article-title {
  font-size: clamp(19px, 2.6vw, 24px);
  color: var(--navy-800);
  font-weight: 800;
  line-height: 1.5;
  margin-bottom: 16px;
}
.article-body { display: grid; grid-template-columns: 1.3fr 1fr; gap: 28px; align-items: start; }
.article-body.no-figure { grid-template-columns: 1fr; }
.article-text p { color: var(--text-soft); font-size: 15px; margin-bottom: 14px; }
.article-text p:last-child { margin-bottom: 0; }
.article-figure {
  background: var(--surface-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 16px;
}
.article-figure figcaption {
  font-size: 12.5px;
  color: var(--text-mute);
  margin-top: 10px;
  line-height: 1.6;
}
.article-core {
  margin-top: 18px;
  padding: 14px 18px;
  background: var(--teal-100);
  border-left: 3px solid var(--teal-500);
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--teal-600);
  font-weight: 600;
}

/* Full long-form article (secondary pages) */
.long-article {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px;
  box-shadow: var(--shadow-sm);
  margin-bottom: 32px;
}
.long-article h2 { font-size: clamp(20px, 2.8vw, 26px); color: var(--navy-800); font-weight: 800; margin-bottom: 10px; }
.long-article .article-meta { margin-bottom: 20px; }
.long-article h4 {
  font-size: 15px;
  color: var(--teal-600);
  font-weight: 700;
  margin: 22px 0 10px;
}
.long-article p { color: var(--text-soft); font-size: 15px; margin-bottom: 14px; }
.long-article .article-core { margin: 18px 0; }

/* Summary cards linking to secondary pages (index page) */
.summary-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 22px;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.summary-card .article-meta { margin-bottom: 0; }
.summary-card h4 { font-size: 16px; color: var(--navy-800); font-weight: 700; line-height: 1.5; }
.summary-card p { color: var(--text-soft); font-size: 14px; }
.summary-card .link-more { color: var(--teal-600); font-weight: 700; font-size: 13.5px; margin-top: auto; }
.summary-card .link-more::after { content: " →"; }

/* Observation column */
.observation {
  border: 1px dashed var(--border-strong);
  border-radius: var(--radius-md);
  padding: 24px 26px;
  background: var(--surface);
}
.observation h4 { color: var(--navy-800); font-size: 16.5px; font-weight: 800; margin-bottom: 10px; line-height: 1.5; }
.observation p { color: var(--text-soft); font-size: 14.5px; margin-bottom: 10px; }

/* ---------------- Tables ---------------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius-md); }
table { width: 100%; border-collapse: collapse; min-width: 560px; font-size: 14px; }
thead th {
  background: var(--navy-800);
  color: #fff;
  text-align: left;
  padding: 12px 16px;
  font-weight: 600;
  white-space: nowrap;
}
tbody td { padding: 12px 16px; border-top: 1px solid var(--border); color: var(--text-soft); }
tbody tr:nth-child(even) { background: var(--surface-alt); }

/* ---------------- Tabs ---------------- */
.tabs { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 20px; }
.tab-btn {
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: 999px;
  padding: 9px 18px;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-soft);
}
.tab-btn[aria-selected="true"] { background: var(--navy-800); color: #fff; border-color: var(--navy-800); }
.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* ---------------- FAQ ---------------- */
.faq-list { display: flex; flex-direction: column; gap: 10px; }
.faq-item { border: 1px solid var(--border); border-radius: var(--radius-md); background: var(--surface); overflow: hidden; }
.faq-q {
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  padding: 18px 22px;
  font-size: 15px;
  font-weight: 700;
  color: var(--navy-800);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}
.faq-q .plus { transition: transform 0.2s; color: var(--teal-600); font-size: 20px; flex-shrink: 0; }
.faq-item[data-open="true"] .plus { transform: rotate(45deg); }
.faq-a { max-height: 0; overflow: hidden; transition: max-height 0.25s ease; }
.faq-a p { padding: 0 22px 18px; color: var(--text-soft); font-size: 14.5px; }

/* ---------------- Assistant demo ---------------- */
.assistant-panel {
  background: var(--navy-900);
  border-radius: var(--radius-lg);
  padding: 30px;
  color: var(--text-invert);
}
.assistant-q-list { display: flex; flex-direction: column; gap: 10px; margin-bottom: 20px; }
.assistant-q {
  text-align: left;
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.14);
  border-radius: var(--radius-sm);
  padding: 12px 16px;
  color: #DCE6F7;
  font-size: 14px;
}
.assistant-q[aria-selected="true"] { background: var(--teal-600); border-color: var(--teal-600); color: #fff; }
.assistant-answer {
  background: rgba(255,255,255,0.05);
  border-left: 3px solid var(--gold-500);
  border-radius: var(--radius-sm);
  padding: 18px 20px;
  font-size: 14.5px;
  color: #E7EDF8;
  line-height: 1.8;
}

/* ---------------- App feature grid ---------------- */
.feature-num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 30px; height: 30px; border-radius: 50%;
  background: var(--navy-800); color: #fff; font-weight: 700; font-size: 13px;
  margin-bottom: 12px;
}
.download-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 34px;
  text-align: center;
}
.download-badges { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; margin: 24px 0; }
.download-badge {
  display: flex; align-items: center; gap: 10px;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  padding: 12px 20px;
  min-width: 180px;
}
.download-badge svg { width: 28px; height: 28px; }
.download-badge .b-title { font-size: 11px; color: var(--text-mute); }
.download-badge .b-name { font-size: 14.5px; font-weight: 700; color: var(--navy-800); }
.notice-box {
  background: var(--gold-100);
  border: 1px solid #E8D6A5;
  border-radius: var(--radius-sm);
  padding: 14px 18px;
  font-size: 13.5px;
  color: #7A5E1E;
  margin-top: 18px;
}

/* ---------------- Company / About ---------------- */
.about-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px;
}
.about-facts { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; margin-top: 24px; }
.about-facts div { border-top: 3px solid var(--gold-500); padding-top: 10px; }
.about-facts .f-label { font-size: 12.5px; color: var(--text-mute); margin-bottom: 4px; }
.about-facts .f-value { font-size: 14.5px; font-weight: 700; color: var(--navy-800); }

.disclaimer {
  font-size: 12.5px;
  color: var(--text-mute);
  border-top: 1px solid var(--border);
  padding-top: 18px;
  margin-top: 18px;
  line-height: 1.8;
}

/* ---------------- Breadcrumb ---------------- */
.breadcrumb { font-size: 13px; color: var(--text-mute); margin-bottom: 8px; }
.breadcrumb a { color: var(--teal-600); font-weight: 600; }

/* ---------------- Footer ---------------- */
.site-footer { background: var(--navy-900); color: #B9C6DE; padding: 56px 0 24px; margin-top: 40px; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1fr; gap: 32px; margin-bottom: 36px; }
.footer-brand { display: flex; align-items: center; gap: 10px; color: #fff; font-weight: 700; font-size: 18px; margin-bottom: 12px; }
.footer-brand svg { width: 32px; height: 32px; }
.footer-col h5 { color: #fff; font-size: 14px; margin-bottom: 14px; letter-spacing: 0.02em; }
.footer-col ul { display: flex; flex-direction: column; gap: 10px; }
.footer-col a, .footer-col span { font-size: 13.5px; color: #A9BAD6; }
.footer-col a:hover { color: var(--gold-500); }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding-top: 20px;
  font-size: 12.5px;
  color: #8497B8;
  line-height: 1.9;
}
.back-top {
  position: fixed;
  right: 22px;
  bottom: 22px;
  width: 46px; height: 46px;
  border-radius: 50%;
  background: var(--navy-800);
  color: #fff;
  border: none;
  display: none;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-lg);
  z-index: 60;
  font-size: 18px;
}
.back-top.show { display: flex; }

/* ---------------- Utility ---------------- */
.mt-0 { margin-top: 0; }
.text-center { text-align: center; }
.divider { height: 1px; background: var(--border); margin: 48px 0; }
.pill-row { display: flex; flex-wrap: wrap; gap: 8px; }
.pill {
  font-size: 12.5px;
  color: var(--teal-600);
  background: var(--teal-100);
  padding: 5px 12px;
  border-radius: 999px;
  font-weight: 600;
}

/* ---------------- Responsive ---------------- */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .about-facts { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 860px) {
  .hero .container { grid-template-columns: 1fr; }
  .hero-art { order: -1; max-width: 340px; margin: 0 auto; }
  .article-body { grid-template-columns: 1fr; }
  .article-body .article-figure { order: -1; }
}
@media (max-width: 720px) {
  .nav-toggle { display: flex; }
  .main-nav {
    position: fixed;
    top: 0; right: 0;
    height: 100vh;
    width: 78%;
    max-width: 320px;
    background: var(--navy-900);
    flex-direction: column;
    align-items: stretch;
    padding: 90px 20px 20px;
    gap: 4px;
    transform: translateX(100%);
    transition: transform 0.25s ease;
    z-index: 55;
  }
  .main-nav.open { transform: translateX(0); }
  .main-nav a { color: #DCE6F7; padding: 14px 16px; font-size: 16px; }
  .main-nav a:hover, .main-nav a[aria-current="page"] { background: rgba(255,255,255,0.08); color: #fff; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: 26px; }
  .about-facts { grid-template-columns: 1fr 1fr; }
  .article { padding: 22px; }
  .long-article { padding: 22px; }
  .section { padding: 46px 0; }
  .hero { padding: 44px 0 52px; }
}
@media (max-width: 480px) {
  .container { padding: 0 16px; }
  .about-facts { grid-template-columns: 1fr; }
  .download-badges { flex-direction: column; align-items: stretch; }
}