/* 迪威国际官网 — 全站样式
   设计方向：全球汽车科技研究中心 / EV Energy Lab / Battery Supply Chain / Autonomous Driving Safety Lab
   配色：暖白 · 汽车深蓝 · 电动青蓝 · 电池绿 · 石墨灰 · 安全橙 */

:root {
  --paper: #f7f5f1;
  --paper-raised: #ffffff;
  --ink: #1c2430;
  --ink-soft: #4b5563;
  --line: #e4e0d8;
  --line-strong: #d3cec2;

  --auto-blue: #12233f;
  --auto-blue-soft: #1f3a5f;
  --ev-cyan: #0ea5b7;
  --ev-cyan-deep: #086b78;
  --battery-green: #2f7d5e;
  --battery-green-soft: #e4f0e9;
  --graphite: #565b61;
  --graphite-soft: #eceae6;
  --safety-orange: #c1601f;
  --safety-orange-soft: #f7e9dd;

  --radius-s: 6px;
  --radius-m: 10px;
  --radius-l: 16px;
  --shadow-card: 0 1px 2px rgba(28,36,48,.06), 0 6px 20px rgba(28,36,48,.05);
  --maxw: 1180px;
  --font-serif: "Songti SC","STSong","SimSun",Georgia,serif;
  --font-sans: -apple-system,"PingFang SC","Microsoft YaHei","Segoe UI",Helvetica,Arial,sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img, svg { max-width: 100%; display: block; }
a { color: var(--ev-cyan-deep); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { font-family: var(--font-serif); color: var(--auto-blue); font-weight: 700; margin: 0 0 .6em; line-height: 1.35; }
p { margin: 0 0 1em; }
ul, ol { margin: 0 0 1em; padding-left: 1.3em; }
.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 ---------- */
.topbar {
  background: var(--auto-blue);
  color: #cfd8e3;
  font-size: 13px;
}
.topbar .container { display:flex; justify-content:space-between; align-items:center; padding-top:6px; padding-bottom:6px; flex-wrap:wrap; gap:6px; }
.topbar span { opacity:.85; }

/* ---------- Header / Nav ---------- */
.site-header {
  background: var(--paper-raised);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 40;
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 76px;
}
.brand { display:flex; align-items:center; gap:10px; }
.brand .logo-mark { width:38px; height:38px; flex:none; }
.brand-text { display:flex; flex-direction:column; line-height:1.2; }
.brand-text strong { font-family: var(--font-serif); font-size:19px; color: var(--auto-blue); }
.brand-text small { font-size:11px; color: var(--ink-soft); letter-spacing:.02em; }

.main-nav { display:flex; }
.main-nav ul { display:flex; gap: 4px; margin:0; padding:0; list-style:none; }
.main-nav a {
  color: var(--ink);
  font-size: 15px;
  padding: 10px 14px;
  border-radius: var(--radius-s);
  white-space: nowrap;
}
.main-nav a:hover, .main-nav a[aria-current="page"] {
  background: var(--graphite-soft);
  color: var(--auto-blue);
  text-decoration: none;
}
.nav-toggle {
  display:none;
  background:none;
  border:1px solid var(--line-strong);
  border-radius: var(--radius-s);
  width:44px; height:40px;
  cursor:pointer;
  position:relative;
}
.nav-toggle span, .nav-toggle span::before, .nav-toggle span::after {
  content:""; position:absolute; left:10px; right:10px; height:2px; background:var(--auto-blue);
}
.nav-toggle span { top:19px; }
.nav-toggle span::before { top:-7px; }
.nav-toggle span::after { top:7px; }

/* ---------- Hero ---------- */
.hero {
  background: linear-gradient(180deg, #eef2ee 0%, var(--paper) 100%);
  border-bottom: 1px solid var(--line);
  padding: 52px 0 44px;
}
.hero .container { display:grid; grid-template-columns: 1.15fr .85fr; gap: 42px; align-items:center; }
.hero h1 { font-size: 32px; margin-bottom: .4em; }
.hero .lede { font-size: 17px; color: var(--ink-soft); max-width: 56ch; }
.hero-tags { display:flex; flex-wrap:wrap; gap:8px; margin-top:18px; }
.hero-tags span {
  font-size: 12.5px;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--paper-raised);
  border: 1px solid var(--line-strong);
  color: var(--ink-soft);
}
.hero-art { justify-self:center; }

/* ---------- Sections ---------- */
.section { padding: 56px 0; }
.section + .section { border-top: 1px solid var(--line); }
.section-alt { background: var(--paper-raised); }
.section-head { max-width: 78ch; margin-bottom: 30px; }
.section-kicker {
  display:inline-block;
  font-size: 12.5px;
  letter-spacing: .06em;
  color: var(--ev-cyan-deep);
  background: rgba(14,165,183,.1);
  padding: 3px 10px;
  border-radius: 999px;
  margin-bottom: 10px;
  font-family: var(--font-sans);
  font-weight: 600;
}
.section-head h2 { font-size: 25px; }
.section-head p { color: var(--ink-soft); font-size: 15.5px; }

/* ---------- Chain / flow diagram strip ---------- */
.chain-strip { display:flex; flex-wrap:wrap; align-items:center; gap:0; margin: 18px 0 8px; }
.chain-node {
  background: var(--paper-raised);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-m);
  padding: 10px 14px;
  font-size: 13.5px;
  color: var(--auto-blue);
  font-weight:600;
}
.chain-arrow { color: var(--line-strong); padding: 0 6px; font-size:16px; }
@media (max-width: 640px) {
  .chain-strip { flex-direction:column; align-items:stretch; }
  .chain-arrow { align-self:center; padding: 2px 0; transform: rotate(90deg); }
}

/* ---------- Article cards / grids ---------- */
.grid { display:grid; gap: 22px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
@media (max-width: 900px) { .grid-3, .grid-2 { grid-template-columns: 1fr; } }

.article-feature {
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius-l);
  padding: 28px 30px;
  box-shadow: var(--shadow-card);
  margin-bottom: 22px;
}
.article-feature .meta { font-size:12.5px; color:var(--ev-cyan-deep); font-weight:600; margin-bottom:6px; letter-spacing:.02em; }
.article-feature h3 { font-size: 21px; margin-bottom:.5em; }
.article-feature .lens {
  display:inline-block;
  font-size:11.5px;
  color: var(--safety-orange);
  border: 1px solid var(--safety-orange-soft);
  background: var(--safety-orange-soft);
  padding: 2px 9px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.article-feature .body p { color: var(--ink); font-size:15.5px; }
.article-feature .callout {
  border-left: 3px solid var(--ev-cyan);
  background: rgba(14,165,183,.06);
  padding: 10px 14px;
  font-size: 14.5px;
  color: var(--ink-soft);
  margin: 14px 0;
  border-radius: 0 var(--radius-s) var(--radius-s) 0;
}
.article-feature .figure { margin: 16px 0; text-align:center; }
.article-feature .figure figcaption { font-size:12.5px; color:var(--ink-soft); margin-top:8px; }
.article-feature .read-link { display:inline-block; margin-top:6px; font-weight:600; }

.article-card {
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius-m);
  padding: 20px 22px;
  box-shadow: var(--shadow-card);
}
.article-card .tag { font-size:11.5px; color:var(--battery-green); font-weight:600; }
.article-card h3 { font-size:17px; margin: 6px 0 8px; }
.article-card p { font-size:14.5px; color:var(--ink-soft); margin-bottom:10px; }
.article-card a.more { font-size:13.5px; font-weight:600; }

/* full secondary-page long article */
.article-full {
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius-l);
  padding: 32px clamp(20px,4vw,44px);
  box-shadow: var(--shadow-card);
  margin-bottom: 28px;
}
.article-full .meta { font-size:13px; color:var(--ev-cyan-deep); font-weight:600; margin-bottom:8px; }
.article-full h2 { font-size:24px; }
.article-full p { font-size:16px; }
.article-full .subhead { font-size:16px; color:var(--auto-blue); font-weight:700; margin: 22px 0 8px; font-family: var(--font-serif); }
.article-full .callout {
  border-left: 3px solid var(--safety-orange);
  background: var(--safety-orange-soft);
  padding: 12px 16px;
  font-size: 15px;
  color: #5c3a1e;
  margin: 16px 0;
  border-radius: 0 var(--radius-s) var(--radius-s) 0;
}
.article-full .figure { margin: 20px 0; text-align:center; }
.article-full .figure figcaption { font-size:13px; color:var(--ink-soft); margin-top:8px; }

/* ---------- Observation column (官网汽车观察) ---------- */
.observation {
  border: 1px dashed var(--line-strong);
  border-radius: var(--radius-m);
  padding: 18px 20px;
  background: #fbfaf7;
}
.observation .tag { font-size:11.5px; color:var(--graphite); font-weight:700; }
.observation h3 { font-size:16.5px; margin: 6px 0 8px; }
.observation p { font-size:14.5px; color:var(--ink-soft); }

/* ---------- Autonomy 2026 panel ---------- */
.autonomy-panel {
  background: var(--auto-blue);
  color: #dbe3ee;
  border-radius: var(--radius-l);
  padding: 32px clamp(20px,4vw,40px);
}
.autonomy-panel h2, .autonomy-panel h3 { color:#fff; }
.autonomy-panel p { color:#c3ceda; font-size:15.5px; }
.autonomy-panel .level-row { display:flex; gap:10px; flex-wrap:wrap; margin: 14px 0 20px; }
.autonomy-panel .level-chip {
  background: rgba(255,255,255,.08);
  border: 1px solid rgba(255,255,255,.18);
  border-radius: var(--radius-s);
  padding: 8px 12px;
  font-size: 13px;
}
.autonomy-panel .level-chip b { color:#8fd7e0; }
.autonomy-subcards { display:grid; grid-template-columns:repeat(3,1fr); gap:16px; margin-top:18px; }
@media (max-width:900px){ .autonomy-subcards{ grid-template-columns:1fr; } }
.autonomy-subcards .sub {
  background: rgba(255,255,255,.06);
  border: 1px solid rgba(255,255,255,.14);
  border-radius: var(--radius-m);
  padding: 16px 18px;
}
.autonomy-subcards .sub h4 { color:#fff; font-size:15px; margin-bottom:6px; }
.autonomy-subcards .sub p { font-size:13.8px; }

/* ---------- FAQ ---------- */
.faq-list { border-top: 1px solid var(--line); }
.faq-item { border-bottom: 1px solid var(--line); }
.faq-q {
  width:100%;
  text-align:left;
  background:none;
  border:none;
  font-family: var(--font-sans);
  font-size: 15.5px;
  font-weight:600;
  color: var(--auto-blue);
  padding: 16px 4px;
  cursor:pointer;
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap: 12px;
}
.faq-q .icon { flex:none; width:20px; height:20px; position:relative; }
.faq-q .icon::before, .faq-q .icon::after {
  content:""; position:absolute; background:var(--ev-cyan-deep); border-radius:2px;
}
.faq-q .icon::before { left:2px; right:2px; top:9px; height:2px; }
.faq-q .icon::after { top:2px; bottom:2px; left:9px; width:2px; transition: transform .18s ease; }
.faq-item[data-open="true"] .icon::after { transform: rotate(90deg); }
.faq-a { max-height:0; overflow:hidden; transition: max-height .22s ease; }
.faq-item[data-open="true"] .faq-a { max-height: 480px; }
.faq-a p { padding: 0 4px 16px; font-size:14.8px; color: var(--ink-soft); }

/* ---------- Tabs (battery chemistry / SDV / ADAS / supply chain) ---------- */
.tabbed { background:var(--paper-raised); border:1px solid var(--line); border-radius:var(--radius-l); padding:24px; box-shadow:var(--shadow-card); }
.tab-buttons { display:flex; flex-wrap:wrap; gap:8px; margin-bottom:18px; }
.tab-btn {
  border:1px solid var(--line-strong);
  background: var(--paper);
  color: var(--ink-soft);
  padding: 8px 14px;
  border-radius: 999px;
  font-size: 13.8px;
  cursor:pointer;
  font-family: var(--font-sans);
}
.tab-btn[aria-selected="true"] {
  background: var(--auto-blue);
  border-color: var(--auto-blue);
  color: #fff;
}
.tab-panel { display:none; }
.tab-panel[data-active="true"] { display:block; }
.tab-panel .row { display:grid; grid-template-columns: 1fr 1fr; gap:22px; align-items:start; }
@media (max-width:800px){ .tab-panel .row{ grid-template-columns:1fr; } }
.spec-list { list-style:none; padding:0; margin:0; }
.spec-list li { display:flex; justify-content:space-between; padding:7px 0; border-bottom:1px dashed var(--line); font-size:14px; }
.spec-list li b { color:var(--auto-blue); }

/* ---------- Charging curve demo ---------- */
.curve-demo { background:var(--paper-raised); border:1px solid var(--line); border-radius:var(--radius-l); padding:24px; box-shadow:var(--shadow-card); }
.curve-controls { display:flex; align-items:center; gap:14px; flex-wrap:wrap; margin-bottom:16px; }
.curve-controls label { font-size:13.5px; color:var(--ink-soft); }
.curve-controls input[type=range] { width:220px; accent-color: var(--ev-cyan-deep); }
.curve-readout { font-size:13.5px; background:var(--graphite-soft); border-radius:var(--radius-s); padding:6px 12px; }
.curve-readout b { color: var(--safety-orange); }
#curveSvg { width:100%; height:auto; }

/* ---------- Supply chain layer toggle ---------- */
.layer-toggle { display:flex; gap:8px; flex-wrap:wrap; margin-bottom:16px; }
.chain-map .layer { display:none; }
.chain-map .layer[data-active="true"] { display:block; }

/* ---------- AI assistant mock ---------- */
.assistant-mock {
  background: var(--auto-blue);
  border-radius: var(--radius-l);
  padding: 22px;
  color:#fff;
}
.assistant-mock .msg { border-radius: var(--radius-m); padding:12px 16px; margin-bottom:12px; font-size:14.5px; max-width:88%; }
.assistant-mock .msg.user { background: rgba(255,255,255,.12); margin-left:auto; }
.assistant-mock .msg.bot { background: rgba(14,165,183,.16); border:1px solid rgba(14,165,183,.35); }
.assistant-mock .prompts { display:flex; flex-wrap:wrap; gap:8px; margin-top:14px; }
.assistant-mock .prompts button {
  background: rgba(255,255,255,.08);
  border:1px solid rgba(255,255,255,.2);
  color:#dbe3ee;
  border-radius:999px;
  padding:6px 12px;
  font-size:12.8px;
  cursor:pointer;
  font-family: var(--font-sans);
}
.assistant-mock .answer { display:none; }
.assistant-mock .answer[data-active="true"] { display:block; }

/* ---------- App mock ---------- */
.app-shell {
  max-width: 340px;
  margin: 0 auto;
  background: var(--paper-raised);
  border: 6px solid var(--auto-blue);
  border-radius: 32px;
  padding: 14px 12px 20px;
  box-shadow: var(--shadow-card);
}
.app-shell .app-top { text-align:center; font-size:12.5px; color:var(--ink-soft); margin-bottom:10px; }
.app-tiles { display:grid; grid-template-columns:repeat(2,1fr); gap:10px; }
.app-tiles .tile {
  background: var(--paper);
  border:1px solid var(--line);
  border-radius: var(--radius-m);
  padding: 12px 10px;
  text-align:center;
  font-size:12.5px;
  color: var(--auto-blue);
  font-weight:600;
}
.app-tiles .tile svg { width:26px; height:26px; margin: 0 auto 6px; }

.download-panel { display:grid; grid-template-columns: repeat(3,1fr); gap:16px; }
@media (max-width:800px){ .download-panel{ grid-template-columns:1fr; } }
.download-panel .entry {
  border:1px solid var(--line);
  background: var(--paper-raised);
  border-radius: var(--radius-m);
  padding: 18px;
  text-align:center;
}
.download-panel .entry svg { width:44px; height:44px; margin:0 auto 10px; }
.download-panel .entry .status {
  display:inline-block;
  margin-top:10px;
  font-size:12.5px;
  color: var(--graphite);
  background: var(--graphite-soft);
  border-radius:999px;
  padding:4px 10px;
}

/* ---------- Stat / badge rows ---------- */
.badge-row { display:flex; flex-wrap:wrap; gap:10px; }
.badge {
  border:1px solid var(--line-strong);
  border-radius: var(--radius-s);
  padding: 6px 12px;
  font-size: 12.8px;
  color: var(--ink-soft);
  background: var(--paper-raised);
}
.badge b { color: var(--auto-blue); }

/* ---------- Table ---------- */
.scroll-table { overflow-x:auto; border:1px solid var(--line); border-radius:var(--radius-m); }
table.data { width:100%; border-collapse:collapse; font-size:14px; min-width:560px; }
table.data th, table.data td { padding:10px 14px; text-align:left; border-bottom:1px solid var(--line); }
table.data th { background: var(--graphite-soft); color:var(--auto-blue); font-family:var(--font-serif); }

/* ---------- Notice blocks ---------- */
.notice {
  border: 1px solid var(--line-strong);
  background: var(--paper-raised);
  border-radius: var(--radius-m);
  padding: 18px 20px;
  font-size: 13.8px;
  color: var(--ink-soft);
}
.notice + .notice { margin-top:12px; }
.notice strong { color: var(--auto-blue); }

/* ---------- Breadcrumb ---------- */
.crumbs { font-size:13px; color:var(--ink-soft); padding: 14px 0 0; }
.crumbs a { color:var(--ink-soft); }

/* ---------- Company / about ---------- */
.about-block { display:grid; grid-template-columns: .9fr 1.1fr; gap:34px; align-items:center; }
@media (max-width:900px){ .about-block{ grid-template-columns:1fr; } }
.fact-list { list-style:none; padding:0; margin:14px 0 0; }
.fact-list li { display:flex; gap:8px; padding:6px 0; font-size:14px; border-bottom:1px dashed var(--line); }
.fact-list li b { color:var(--auto-blue); min-width:88px; flex:none; }

/* ---------- Footer ---------- */
.site-footer { background: var(--auto-blue); color:#b9c4d2; padding: 44px 0 26px; font-size:13.5px; }
.footer-grid { display:grid; grid-template-columns: 1.3fr 1fr 1fr 1fr; gap:28px; }
@media (max-width:900px){ .footer-grid{ grid-template-columns: 1fr 1fr; } }
@media (max-width:560px){ .footer-grid{ grid-template-columns: 1fr; } }
.footer-grid h4 { color:#fff; font-size:14.5px; margin-bottom:12px; font-family:var(--font-sans); }
.footer-grid ul { list-style:none; padding:0; margin:0; }
.footer-grid li { margin-bottom:8px; }
.footer-grid a { color:#b9c4d2; }
.footer-brand p { color:#98a5b7; font-size:13px; max-width:40ch; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,.12);
  margin-top: 30px;
  padding-top: 18px;
  display:flex;
  justify-content:space-between;
  flex-wrap:wrap;
  gap:10px;
  color:#8b98ab;
  font-size:12.5px;
}
.icp-slot { color:#8b98ab; }

/* ---------- Back to top ---------- */
.back-top {
  position: fixed;
  right: 22px;
  bottom: 22px;
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: var(--auto-blue);
  color: #fff;
  border: none;
  cursor: pointer;
  display: none;
  align-items:center;
  justify-content:center;
  box-shadow: var(--shadow-card);
  z-index: 30;
}
.back-top.show { display:flex; }
.back-top svg { width:18px; height:18px; }

/* ---------- Buttons ---------- */
.btn {
  display:inline-block;
  padding: 10px 18px;
  border-radius: var(--radius-s);
  font-size:14.5px;
  font-weight:600;
  border: 1px solid transparent;
  cursor: pointer;
  font-family: var(--font-sans);
}
.btn-primary { background: var(--auto-blue); color:#fff; }
.btn-primary:hover { background: var(--auto-blue-soft); text-decoration:none; }
.btn-line { border-color: var(--line-strong); color: var(--auto-blue); background:var(--paper-raised); }
.btn-line:hover { border-color: var(--auto-blue); text-decoration:none; }

/* ---------- Responsive nav ---------- */
@media (max-width: 980px) {
  .main-nav { position: fixed; top:76px; left:0; right:0; bottom:0; background:var(--paper-raised);
    transform: translateX(100%); transition: transform .22s ease; overflow-y:auto; border-top:1px solid var(--line); }
  .main-nav.open { transform: translateX(0); }
  .main-nav ul { flex-direction:column; padding: 12px 16px; gap:2px; }
  .main-nav a { display:block; padding:14px 10px; font-size:16.5px; border-bottom:1px solid var(--line); border-radius:0; }
  .nav-toggle { display:block; }
  .hero .container { grid-template-columns: 1fr; }
  .hero-art { order:-1; max-width:220px; }
}
@media (max-width: 640px) {
  .container { padding: 0 16px; }
  .hero { padding: 36px 0 30px; }
  .hero h1 { font-size: 25px; }
  .section { padding: 40px 0; }
  .article-feature, .article-full { padding: 20px 18px; }
  .about-block, .footer-grid { gap:20px; }
}