/* ==========================================================================
   鼎天国际官网 - style.css
   原生 CSS3，无远程字体、无框架依赖
   ========================================================================== */

:root {
  --bg: #070c17;
  --bg-alt: #0b1220;
  --panel: #0e1730;
  --panel-2: #101c3a;
  --border: #1d2c4d;
  --border-soft: #16223f;
  --text: #e8eefc;
  --text-muted: #93a3c4;
  --text-dim: #64729a;
  --cyan: #3fd0f2;
  --amber: #f6ab3f;
  --violet: #a486f2;
  --green: #3fdba0;
  --red: #f2685f;
  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 9px;
  --maxw: 1180px;
  --header-h: 68px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--cyan); text-decoration: none; }
a:hover { text-decoration: underline; }
ul, ol { padding-left: 1.3em; }
h1, h2, h3, h4 { line-height: 1.4; font-weight: 700; margin: 0 0 .6em; color: var(--text); }
p { margin: 0 0 1em; }

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

/* ---------------- skip link ---------------- */
.skip-link {
  position: absolute; left: -999px; top: 0; background: var(--cyan); color: #04121c;
  padding: 10px 16px; z-index: 999; border-radius: 0 0 8px 0; font-weight: 700;
}
.skip-link:focus { left: 0; }

/* ---------------- header / nav ---------------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(7, 12, 23, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-soft);
  height: var(--header-h);
}
.site-header .container {
  height: 100%; display: flex; align-items: center; justify-content: space-between; gap: 20px;
}
.brand { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.brand img { height: 40px; width: auto; }
.main-nav { display: flex; }
.main-nav ul { list-style: none; margin: 0; padding: 0; display: flex; gap: 6px; }
.main-nav a {
  color: var(--text-muted); font-weight: 600; font-size: 15px; padding: 9px 14px;
  border-radius: 999px; transition: all .15s ease; text-decoration: none; white-space: nowrap;
}
.main-nav a:hover, .main-nav a[aria-current="page"] {
  color: var(--text); background: var(--panel-2); text-decoration: none;
}
.nav-toggle {
  display: none; background: var(--panel); border: 1px solid var(--border); border-radius: 10px;
  width: 42px; height: 42px; color: var(--text); font-size: 20px; cursor: pointer;
}

/* ---------------- hero ---------------- */
.hero {
  padding: 56px 0 40px;
  background: radial-gradient(circle at 18% 0%, rgba(63,208,242,0.10), transparent 55%),
              radial-gradient(circle at 85% 20%, rgba(164,134,242,0.10), transparent 50%);
}
.hero-grid { display: grid; grid-template-columns: 1.05fr 0.95fr; gap: 40px; align-items: center; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px; font-size: 12.5px; font-weight: 700;
  color: var(--cyan); background: rgba(63,208,242,0.10); border: 1px solid rgba(63,208,242,0.28);
  padding: 5px 12px; border-radius: 999px; margin-bottom: 16px; letter-spacing: .5px;
}
.hero h1 { font-size: clamp(26px, 4vw, 38px); margin-bottom: 16px; }
.hero .lead { font-size: 17px; color: var(--text-muted); max-width: 56ch; }
.hero-actions { display: flex; gap: 12px; margin-top: 22px; flex-wrap: wrap; }

.btn {
  display: inline-flex; align-items: center; gap: 8px; padding: 12px 22px; border-radius: 999px;
  font-weight: 700; font-size: 15px; border: 1px solid transparent; cursor: pointer;
}
.btn-primary { background: linear-gradient(120deg, var(--cyan), var(--violet)); color: #04121c; }
.btn-primary:hover { text-decoration: none; opacity: .92; }
.btn-ghost { background: transparent; border-color: var(--border); color: var(--text); }
.btn-ghost:hover { text-decoration: none; border-color: var(--cyan); color: var(--cyan); }

/* ---------------- section ---------------- */
section { padding: 56px 0; border-top: 1px solid var(--border-soft); }
section:first-of-type { border-top: none; }
.section-head { max-width: 760px; margin-bottom: 32px; }
.section-head .kicker {
  font-size: 12.5px; font-weight: 700; color: var(--amber); letter-spacing: 1px; text-transform: uppercase;
  margin-bottom: 8px; display: block;
}
.section-head h2 { font-size: clamp(22px, 3vw, 30px); margin-bottom: 10px; }
.section-head p { color: var(--text-muted); margin: 0; }

/* ---------------- panel / card ---------------- */
.panel {
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 26px;
}
.diagram-figure { margin: 0; }
.diagram-figure img { border-radius: var(--radius-lg); border: 1px solid var(--border); background: var(--panel); }
.diagram-figure figcaption {
  margin-top: 10px; font-size: 13px; color: var(--text-dim); text-align: center;
}

/* ---------------- article (feature / long-form) ---------------- */
.feature-article {
  display: grid; grid-template-columns: 1.15fr 0.85fr; gap: 32px; align-items: start;
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-lg);
  padding: 30px; margin-bottom: 26px;
}
.feature-article .meta {
  display: flex; gap: 10px; align-items: center; font-size: 12.5px; color: var(--text-dim); margin-bottom: 12px;
  flex-wrap: wrap;
}
.feature-article .meta .tag {
  background: rgba(63,208,242,0.10); color: var(--cyan); border: 1px solid rgba(63,208,242,0.25);
  padding: 3px 10px; border-radius: 999px; font-weight: 700;
}
.feature-article h3 { font-size: clamp(19px, 2.4vw, 24px); margin-bottom: 14px; }
.feature-article .summary { color: var(--text-muted); }
.feature-article .body-preview { color: var(--text); }
.feature-article .insight {
  border-left: 3px solid var(--amber); padding: 4px 0 4px 14px; margin: 16px 0; color: var(--text-muted);
  font-size: 14.5px; font-style: normal;
}
.feature-article .art-links { margin-top: 16px; display: flex; gap: 16px; flex-wrap: wrap; font-size: 14px; }
.feature-article .art-media { position: sticky; top: calc(var(--header-h) + 20px); }
.feature-article.reverse { grid-template-columns: 0.85fr 1.15fr; }
.feature-article.reverse .art-media { order: -1; }

.stack-list { list-style: none; margin: 0; padding: 0; }
.stack-list li {
  display: flex; gap: 12px; padding: 10px 0; border-bottom: 1px dashed var(--border-soft); font-size: 14.5px;
}
.stack-list li:last-child { border-bottom: none; }
.stack-list .n {
  flex-shrink: 0; width: 26px; height: 26px; border-radius: 50%; background: var(--panel-2);
  border: 1px solid var(--border); display: flex; align-items: center; justify-content: center;
  font-size: 12px; font-weight: 700; color: var(--cyan);
}

/* ---------------- observation column (官网科技观察 / small article) ---------------- */
.obs-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.obs-card {
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-md); padding: 22px;
}
.obs-card .meta { font-size: 12px; color: var(--text-dim); margin-bottom: 10px; }
.obs-card h3 { font-size: 17px; margin-bottom: 10px; }
.obs-card p { color: var(--text-muted); font-size: 14.5px; margin-bottom: 0; }

/* ---------------- article summary / roundup cards (二级页面回流) ---------------- */
.roundup-block { margin-bottom: 34px; }
.roundup-head { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; margin-bottom: 16px; flex-wrap: wrap; }
.roundup-head h3 { font-size: 19px; margin: 0; }
.roundup-head .more { font-size: 13.5px; color: var(--cyan); font-weight: 600; }
.roundup-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.roundup-card {
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-md); padding: 18px;
  display: flex; flex-direction: column; gap: 8px;
}
.roundup-card .meta { font-size: 11.5px; color: var(--text-dim); }
.roundup-card h4 { font-size: 15.5px; margin: 0; }
.roundup-card p { font-size: 13.5px; color: var(--text-muted); margin: 0; flex-grow: 1; }
.roundup-card .link { font-size: 13px; font-weight: 700; }

/* ---------------- full article page blocks (secondary pages) ---------------- */
.long-article {
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-lg);
  padding: 32px; margin-bottom: 30px;
}
.long-article .meta { font-size: 12.5px; color: var(--text-dim); margin-bottom: 10px; display:flex; gap:10px; flex-wrap:wrap; align-items:center;}
.long-article .meta .tag { background: rgba(63,208,242,0.10); color: var(--cyan); border: 1px solid rgba(63,208,242,0.25); padding: 3px 10px; border-radius: 999px; font-weight: 700; }
.long-article h2 { font-size: clamp(20px, 2.6vw, 27px); }
.long-article h4 { font-size: 16px; color: var(--cyan); margin-top: 1.6em; }
.long-article figure { margin: 20px 0; }
.long-article .callout {
  background: var(--panel-2); border: 1px solid var(--border); border-left: 3px solid var(--amber);
  border-radius: var(--radius-sm); padding: 14px 18px; margin: 18px 0; font-size: 14.5px; color: var(--text-muted);
}
.long-article .source-note { font-size: 12.5px; color: var(--text-dim); border-top: 1px dashed var(--border-soft); padding-top: 12px; margin-top: 20px; }

/* ---------------- concept Q&A list (是什么) ---------------- */
.concept-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; }
.concept-item {
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-md); padding: 18px 20px;
}
.concept-item h4 { margin: 0 0 8px; font-size: 15px; color: var(--text); }
.concept-item p { margin: 0; font-size: 14px; color: var(--text-muted); }

/* ---------------- comparison table ---------------- */
.table-wrap { overflow-x: auto; border-radius: var(--radius-md); border: 1px solid var(--border); }
table.cmp { width: 100%; border-collapse: collapse; min-width: 560px; font-size: 14.5px; }
table.cmp th, table.cmp td { padding: 12px 16px; text-align: left; border-bottom: 1px solid var(--border-soft); }
table.cmp th { background: var(--panel-2); color: var(--text); font-weight: 700; }
table.cmp td { color: var(--text-muted); }
table.cmp tr:last-child td { border-bottom: none; }

/* ---------------- tabs ---------------- */
.tabs { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 18px; }
.tab-btn {
  background: var(--panel); border: 1px solid var(--border); color: var(--text-muted); padding: 9px 16px;
  border-radius: 999px; font-size: 13.5px; font-weight: 700; cursor: pointer;
}
.tab-btn[aria-selected="true"] { background: var(--cyan); color: #04121c; border-color: var(--cyan); }
.tab-panel { display: none; }
.tab-panel.is-active { display: block; }

/* ---------------- FAQ ---------------- */
.faq-list { display: flex; flex-direction: column; gap: 10px; }
.faq-item { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-md); overflow: hidden; }
.faq-q {
  width: 100%; text-align: left; background: none; border: none; color: var(--text); font-size: 15px;
  font-weight: 700; padding: 16px 20px; cursor: pointer; display: flex; justify-content: space-between; gap: 14px;
  align-items: center;
}
.faq-q .ico { flex-shrink: 0; color: var(--cyan); transition: transform .18s ease; font-size: 18px; }
.faq-item[data-open="true"] .ico { transform: rotate(45deg); }
.faq-a { padding: 0 20px; max-height: 0; overflow: hidden; transition: all .2s ease; color: var(--text-muted); font-size: 14.5px; }
.faq-item[data-open="true"] .faq-a { padding: 0 20px 18px; max-height: 600px; }

/* ---------------- FAQ two-column layout on wide screens ---------------- */
.faq-columns { display: grid; grid-template-columns: 1fr 1fr; gap: 10px 20px; }
.faq-columns .faq-list { display: contents; }

/* ---------------- chip badges / icon grid (app features, expo tags) ---------------- */
.icon-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
.icon-card {
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-md);
  padding: 18px; text-align: center;
}
.icon-card img { margin: 0 auto 10px; height: 110px; }
.icon-card h4 { font-size: 14.5px; margin: 0 0 4px; }
.icon-card p { font-size: 12.5px; color: var(--text-muted); margin: 0; }

/* ---------------- status badges (expo) ---------------- */
.badge { display: inline-flex; align-items: center; gap: 6px; font-size: 12px; font-weight: 700; padding: 4px 10px; border-radius: 999px; }
.badge-upcoming { background: rgba(246,171,63,0.14); color: var(--amber); border: 1px solid rgba(246,171,63,0.35); }
.badge-ongoing { background: rgba(63,208,242,0.14); color: var(--cyan); border: 1px solid rgba(63,208,242,0.35); }
.badge-completed { background: rgba(63,219,160,0.14); color: var(--green); border: 1px solid rgba(63,219,160,0.35); }

/* ---------------- expo event cards ---------------- */
.expo-card { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 24px; margin-bottom: 18px; }
.expo-card-head { display: flex; justify-content: space-between; align-items: flex-start; gap: 14px; flex-wrap: wrap; margin-bottom: 12px; }
.expo-card-head h3 { margin: 0; font-size: 19px; }
.expo-card .expo-meta { font-size: 13px; color: var(--text-dim); margin-bottom: 12px; }
.expo-status-filter { display: flex; gap: 8px; margin-bottom: 22px; flex-wrap: wrap; }

/* ---------------- AI assistant demo block ---------------- */
.assistant-demo { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 26px; }
.assistant-chat { display: flex; flex-direction: column; gap: 14px; margin-bottom: 18px; }
.chat-bubble { max-width: 82%; padding: 12px 16px; border-radius: 14px; font-size: 14.5px; }
.chat-user { align-self: flex-end; background: linear-gradient(120deg, var(--cyan), var(--violet)); color: #04121c; font-weight: 600; }
.chat-ai { align-self: flex-start; background: var(--panel-2); border: 1px solid var(--border); color: var(--text); }
.chat-ai .verdict-row { display: flex; gap: 8px; margin-top: 10px; flex-wrap: wrap; }
.vchip { font-size: 11px; font-weight: 700; padding: 3px 9px; border-radius: 999px; }
.vchip-current { background: rgba(63,219,160,0.14); color: var(--green); }
.vchip-demo { background: rgba(63,208,242,0.14); color: var(--cyan); }
.vchip-roadmap { background: rgba(246,171,63,0.14); color: var(--amber); }
.assistant-suggestions { display: flex; gap: 8px; flex-wrap: wrap; }
.sugg-btn {
  background: var(--panel-2); border: 1px solid var(--border); color: var(--text-muted); padding: 8px 14px;
  border-radius: 999px; font-size: 13px; cursor: pointer;
}
.sugg-btn:hover { color: var(--cyan); border-color: var(--cyan); }

/* ---------------- app feature grid + download ---------------- */
.download-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.download-card { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius-md); padding: 20px; text-align: center; }
.download-card img { height: 130px; margin: 0 auto 12px; }
.download-note { font-size: 12.5px; color: var(--text-dim); margin-top: 8px; }

/* ---------------- FAQ / company / footer ---------------- */
.company-box { display: grid; grid-template-columns: 1fr 1fr; gap: 30px; align-items: center; }
.company-facts { list-style: none; margin: 18px 0 0; padding: 0; font-size: 14px; color: var(--text-muted); }
.company-facts li { display: flex; gap: 8px; padding: 7px 0; border-bottom: 1px dashed var(--border-soft); }
.company-facts li span:first-child { color: var(--text-dim); flex-shrink: 0; width: 108px; }

footer.site-footer { border-top: 1px solid var(--border-soft); padding: 40px 0 26px; background: var(--bg-alt); }
.footer-grid { display: grid; grid-template-columns: 1.4fr repeat(3, 1fr); gap: 28px; margin-bottom: 26px; }
.footer-col h5 { color: var(--text); font-size: 13.5px; margin-bottom: 12px; }
.footer-col ul { list-style: none; margin: 0; padding: 0; }
.footer-col li { margin-bottom: 8px; }
.footer-col a { color: var(--text-muted); font-size: 13.5px; }
.footer-col a:hover { color: var(--cyan); }
.footer-bottom {
  border-top: 1px solid var(--border-soft); padding-top: 18px; font-size: 12.5px; color: var(--text-dim);
  display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap;
}
.disclaimer { font-size: 12px; color: var(--text-dim); max-width: 900px; margin-top: 10px; }

.back-to-top {
  position: fixed; right: 22px; bottom: 22px; width: 44px; height: 44px; border-radius: 50%;
  background: var(--panel); border: 1px solid var(--border); color: var(--cyan); font-size: 18px;
  display: none; align-items: center; justify-content: center; cursor: pointer; z-index: 90;
}
.back-to-top.show { display: flex; }

.breadcrumb { font-size: 13px; color: var(--text-dim); padding: 16px 0 0; }
.breadcrumb a { color: var(--text-dim); }
.breadcrumb a:hover { color: var(--cyan); }

.pill-row { display: flex; gap: 8px; flex-wrap: wrap; margin: 10px 0 0; }
.pill { font-size: 12.5px; background: var(--panel-2); border: 1px solid var(--border); color: var(--text-muted); padding: 4px 11px; border-radius: 999px; }

/* ---------------- utility ---------------- */
.mt-0 { margin-top: 0; }
.text-muted { color: var(--text-muted); }
.small { font-size: 13px; }
.center { text-align: center; }

/* ==========================================================================
   Responsive
   ========================================================================== */
@media (max-width: 1024px) {
  .obs-grid, .roundup-grid { grid-template-columns: repeat(2, 1fr); }
  .icon-grid { grid-template-columns: repeat(3, 1fr); }
  .download-grid { grid-template-columns: repeat(3, 1fr); }
  .concept-grid { grid-template-columns: 1fr; }
}

@media (max-width: 860px) {
  .main-nav { position: fixed; inset: var(--header-h) 0 0 0; background: var(--bg); padding: 18px 24px;
    transform: translateY(-8px); opacity: 0; pointer-events: none; transition: all .16s ease; overflow-y: auto; }
  .main-nav.open { transform: translateY(0); opacity: 1; pointer-events: auto; }
  .main-nav ul { flex-direction: column; gap: 4px; }
  .main-nav a { display: block; padding: 14px 16px; font-size: 16px; }
  .nav-toggle { display: block; }

  .hero-grid { grid-template-columns: 1fr; }
  .feature-article, .feature-article.reverse { grid-template-columns: 1fr; }
  .feature-article .art-media { order: -1; position: static; }
  .obs-grid, .roundup-grid { grid-template-columns: 1fr; }
  .icon-grid { grid-template-columns: repeat(2, 1fr); }
  .download-grid { grid-template-columns: 1fr; }
  .company-box { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .faq-columns { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .container { padding: 0 16px; }
  .footer-grid { grid-template-columns: 1fr; }
  .icon-grid { grid-template-columns: 1fr 1fr; }
  section { padding: 40px 0; }
  .hero { padding: 40px 0 28px; }
  .long-article, .feature-article, .panel { padding: 20px; }
}