/* ==========================================================================
   迪威国际官网 — 全站样式
   diwei-aviation-ai / static/css/style.css
   原生 CSS3，无远程字体、无框架依赖
   ========================================================================== */

:root{
  --c-bg:#F7F5EF;
  --c-bg-alt:#EFEEE6;
  --c-surface:#FFFFFF;
  --c-navy:#0B2545;
  --c-navy-deep:#081A33;
  --c-sky:#2E86AB;
  --c-sky-light:#5FA8C9;
  --c-radar:#CFEFF3;
  --c-radar-deep:#9FDCE4;
  --c-graphite:#3B3F45;
  --c-graphite-light:#6B7178;
  --c-safety:#E2701E;
  --c-safety-deep:#C25A12;
  --c-line:#E1DED2;
  --c-line-strong:#CFCABA;
  --c-text:#232A32;
  --c-text-soft:#565F68;
  --c-text-inverse:#F4F7F9;
  --radius-s:6px;
  --radius-m:12px;
  --radius-l:20px;
  --shadow-s:0 1px 3px rgba(11,37,69,0.08);
  --shadow-m:0 6px 24px rgba(11,37,69,0.10);
  --font-base: "Segoe UI","PingFang SC","Microsoft YaHei","Noto Sans SC",-apple-system,BlinkMacSystemFont,sans-serif;
  --maxw:1180px;
}

*,*::before,*::after{ box-sizing:border-box; }
html{ scroll-behavior:smooth; }
body{
  margin:0;
  font-family:var(--font-base);
  background:var(--c-bg);
  color:var(--c-text);
  line-height:1.75;
  font-size:16px;
  -webkit-font-smoothing:antialiased;
  overflow-x:hidden;
}
img,svg{ max-width:100%; height:auto; display:block; }
a{ color:var(--c-sky); text-decoration:none; }
a:hover{ text-decoration:underline; }
ul,ol{ padding-left:1.3em; }
h1,h2,h3,h4{ color:var(--c-navy); line-height:1.35; margin:0 0 .6em; font-weight:700; }
p{ margin:0 0 1em; }
.container{ max-width:var(--maxw); margin:0 auto; padding:0 20px; }
.visually-hidden{ position:absolute; width:1px; height:1px; overflow:hidden; clip:rect(0 0 0 0); white-space:nowrap; }

/* ---------- 顶部导航 ---------- */
.site-header{
  position:sticky; top:0; z-index:100;
  background:rgba(247,245,239,0.96);
  border-bottom:1px solid var(--c-line);
  backdrop-filter:saturate(160%) blur(6px);
}
.nav-bar{
  display:flex; align-items:center; justify-content:space-between;
  max-width:var(--maxw); margin:0 auto; padding:12px 20px;
}
.brand{ display:flex; align-items:center; gap:10px; }
.brand img{ width:38px; height:38px; }
.brand-text{ font-weight:700; color:var(--c-navy); font-size:1.15rem; letter-spacing:.5px; }
.brand-text small{ display:block; font-weight:400; font-size:.62rem; color:var(--c-text-soft); letter-spacing:1px; }
.nav-toggle{
  display:none; background:none; border:1px solid var(--c-line-strong); border-radius:var(--radius-s);
  width:42px; height:38px; cursor:pointer; position:relative;
}
.nav-toggle span,.nav-toggle span::before,.nav-toggle span::after{
  content:""; position:absolute; left:9px; right:9px; height:2px; background:var(--c-navy);
}
.nav-toggle span{ top:18px; }
.nav-toggle span::before{ top:-7px; }
.nav-toggle span::after{ top:7px; }
.nav-links{ display:flex; gap:6px; flex-wrap:wrap; }
.nav-links a{
  color:var(--c-graphite); font-size:.93rem; padding:9px 12px; border-radius:var(--radius-s);
  white-space:nowrap;
}
.nav-links a:hover, .nav-links a.active{ background:var(--c-radar); color:var(--c-navy); text-decoration:none; }

/* ---------- Hero ---------- */
.hero{
  background:linear-gradient(150deg,var(--c-navy) 0%,var(--c-navy-deep) 60%,#062038 100%);
  color:var(--c-text-inverse); padding:56px 0 64px; position:relative; overflow:hidden;
}
.hero .container{ display:grid; grid-template-columns:1.15fr .85fr; gap:36px; align-items:center; position:relative; z-index:2; }
.hero-eyebrow{ color:var(--c-radar-deep); font-size:.85rem; letter-spacing:2px; text-transform:uppercase; margin-bottom:14px; }
.hero h1{ color:#fff; font-size:2.05rem; margin-bottom:.5em; }
.hero p.lead{ color:#D4E1EB; font-size:1.02rem; max-width:52ch; }
.hero-art{ background:rgba(255,255,255,0.05); border-radius:var(--radius-l); padding:14px; border:1px solid rgba(255,255,255,0.12); }
.hero-tags{ display:flex; gap:8px; flex-wrap:wrap; margin-top:18px; }
.hero-tags span{
  font-size:.78rem; padding:5px 11px; border-radius:999px; border:1px solid rgba(255,255,255,0.25); color:#CFE3EE;
}
.btn-row{ display:flex; gap:12px; margin-top:24px; flex-wrap:wrap; }
.btn{
  display:inline-block; padding:11px 22px; border-radius:999px; font-weight:600; font-size:.94rem;
  border:1px solid transparent; cursor:pointer;
}
.btn-primary{ background:var(--c-safety); color:#fff; }
.btn-primary:hover{ background:var(--c-safety-deep); text-decoration:none; }
.btn-ghost{ background:transparent; color:#fff; border-color:rgba(255,255,255,0.4); }
.btn-ghost:hover{ background:rgba(255,255,255,0.1); text-decoration:none; }
.btn-outline{ background:transparent; color:var(--c-navy); border-color:var(--c-navy); }
.btn-outline:hover{ background:var(--c-navy); color:#fff; text-decoration:none; }

/* ---------- Section 基础 ---------- */
.section{ padding:56px 0; }
.section-alt{ background:var(--c-surface); }
.section-head{ max-width:74ch; margin-bottom:32px; }
.section-head .kicker{
  display:inline-block; font-size:.78rem; letter-spacing:1.5px; color:var(--c-safety); font-weight:700;
  text-transform:uppercase; margin-bottom:10px;
}
.section-head h2{ font-size:1.55rem; margin-bottom:.4em; }
.section-head p{ color:var(--c-text-soft); }

/* ---------- 航空运行链条 ---------- */
.chain-strip{
  display:flex; flex-wrap:wrap; gap:6px; align-items:center; justify-content:center;
  background:var(--c-surface); border:1px solid var(--c-line); border-radius:var(--radius-l);
  padding:22px; margin:0 0 40px;
}
.chain-strip .node{
  font-size:.86rem; padding:8px 14px; border-radius:999px; background:var(--c-radar); color:var(--c-navy); font-weight:600;
}
.chain-strip .arrow{ color:var(--c-safety); font-weight:700; }

/* ---------- 文章卡片（首页摘要） ---------- */
.article-grid{ display:grid; grid-template-columns:1fr; gap:28px; }
.feature-article{
  background:var(--c-surface); border:1px solid var(--c-line); border-radius:var(--radius-l);
  padding:28px; display:grid; grid-template-columns:1fr 260px; gap:26px;
}
.feature-article .meta{ display:flex; gap:10px; align-items:center; font-size:.82rem; color:var(--c-text-soft); margin-bottom:10px; flex-wrap:wrap; }
.feature-article .meta .tag{ background:var(--c-radar); color:var(--c-navy); padding:3px 10px; border-radius:999px; font-weight:600; }
.feature-article h3{ font-size:1.28rem; margin-bottom:.5em; }
.feature-article .abstract{ color:var(--c-text); }
.feature-article .preview{ color:var(--c-text-soft); border-top:1px dashed var(--c-line-strong); margin-top:14px; padding-top:14px; }
.feature-article .art-figure{ background:var(--c-bg-alt); border-radius:var(--radius-m); padding:14px; align-self:start; }
.feature-article .art-figure figcaption{ font-size:.78rem; color:var(--c-text-soft); margin-top:8px; }
.feature-article .read-more{ display:inline-block; margin-top:14px; font-weight:600; }

/* ---------- 官网观察（首页全文） ---------- */
.observe-card{
  background:var(--c-bg-alt); border-left:4px solid var(--c-safety); border-radius:0 var(--radius-m) var(--radius-m) 0;
  padding:22px 26px; margin-bottom:20px;
}
.observe-card h3{ font-size:1.08rem; }
.observe-card .meta{ font-size:.8rem; color:var(--c-text-soft); margin-bottom:8px; }

/* ---------- 二级页面摘要回流卡片 ---------- */
.rollup-grid{ display:grid; grid-template-columns:repeat(3,1fr); gap:20px; }
.rollup-card{
  background:var(--c-surface); border:1px solid var(--c-line); border-radius:var(--radius-m); padding:20px;
  display:flex; flex-direction:column;
}
.rollup-card .meta{ font-size:.78rem; color:var(--c-text-soft); margin-bottom:6px; }
.rollup-card h4{ font-size:1.02rem; margin-bottom:.5em; }
.rollup-card p{ color:var(--c-text-soft); font-size:.92rem; flex:1; }
.rollup-card a.more{ font-weight:600; font-size:.9rem; margin-top:8px; }
.rollup-section h3.rollup-title{
  display:flex; align-items:center; gap:10px; color:var(--c-navy); font-size:1.15rem; margin:34px 0 16px;
}
.rollup-section h3.rollup-title::before{ content:""; width:6px; height:20px; background:var(--c-safety); border-radius:3px; display:inline-block; }

/* ---------- 全文文章排版（二级页面） ---------- */
.article-full{
  background:var(--c-surface); border:1px solid var(--c-line); border-radius:var(--radius-l);
  padding:32px; margin-bottom:34px;
}
.article-full .meta{ font-size:.84rem; color:var(--c-text-soft); margin-bottom:6px; display:flex; gap:10px; flex-wrap:wrap; }
.article-full .meta .tag{ background:var(--c-radar); color:var(--c-navy); padding:3px 10px; border-radius:999px; font-weight:600; }
.article-full h2{ font-size:1.4rem; }
.article-full h3.sub{ font-size:1.08rem; color:var(--c-navy); margin-top:1.4em; }
.article-full .callout{
  background:var(--c-bg-alt); border-left:3px solid var(--c-sky); padding:14px 18px; border-radius:0 var(--radius-s) var(--radius-s) 0;
  color:var(--c-text-soft); font-size:.95rem; margin:1.2em 0;
}
.article-full .figure-wrap{ margin:20px 0; background:var(--c-bg-alt); border-radius:var(--radius-m); padding:18px; }
.article-full .figure-wrap figcaption{ font-size:.8rem; color:var(--c-text-soft); margin-top:10px; }
.back-to-index{ font-size:.88rem; font-weight:600; }

/* ---------- 时间线 / 关键路径组件 ---------- */
.timeline{ display:flex; flex-wrap:wrap; gap:0; align-items:stretch; }
.timeline .step{
  flex:1 1 120px; background:var(--c-surface); border:1px solid var(--c-line); padding:14px 12px; text-align:center;
  font-size:.82rem; position:relative;
}
.timeline .step + .step{ border-left:none; }
.timeline .step .n{ display:block; font-weight:700; color:var(--c-navy); margin-bottom:4px; }
.timeline .step.crit{ background:#FBEAE0; border-color:var(--c-safety); color:var(--c-safety-deep); font-weight:700; }

/* ---------- Tabs / 切换按钮（交互图） ---------- */
.tabbed-figure{ background:var(--c-surface); border:1px solid var(--c-line); border-radius:var(--radius-l); padding:22px; }
.tab-buttons{ display:flex; gap:8px; flex-wrap:wrap; margin-bottom:16px; }
.tab-buttons button{
  border:1px solid var(--c-line-strong); background:var(--c-bg); color:var(--c-graphite); padding:8px 14px;
  border-radius:999px; font-size:.86rem; cursor:pointer;
}
.tab-buttons button.active{ background:var(--c-navy); color:#fff; border-color:var(--c-navy); }
.tab-panel{ display:none; }
.tab-panel.active{ display:block; }

/* ---------- 表格横向滚动 ---------- */
.table-scroll{ overflow-x:auto; border:1px solid var(--c-line); border-radius:var(--radius-m); }
.table-scroll table{ border-collapse:collapse; width:100%; min-width:560px; font-size:.9rem; }
.table-scroll th,.table-scroll td{ padding:10px 14px; border-bottom:1px solid var(--c-line); text-align:left; white-space:nowrap; }
.table-scroll th{ background:var(--c-bg-alt); color:var(--c-navy); }
.table-scroll td:first-child, .table-scroll th:first-child{ white-space:normal; }

/* ---------- FAQ 手风琴 ---------- */
.faq-list{ border-top:1px solid var(--c-line); }
.faq-item{ border-bottom:1px solid var(--c-line); }
.faq-q{
  width:100%; text-align:left; background:none; border:none; padding:16px 4px; font-size:.98rem; font-weight:600;
  color:var(--c-navy); cursor:pointer; display:flex; justify-content:space-between; gap:10px; align-items:center;
}
.faq-q::after{ content:"+"; font-size:1.3rem; color:var(--c-safety); flex:none; }
.faq-item.open .faq-q::after{ content:"−"; }
.faq-a{ max-height:0; overflow:hidden; transition:max-height .25s ease; color:var(--c-text-soft); font-size:.92rem; padding:0 4px; }
.faq-item.open .faq-a{ padding-bottom:16px; }

/* ---------- AI 助手演示 ---------- */
.assistant-demo{ background:var(--c-navy); border-radius:var(--radius-l); padding:26px; color:#fff; }
.assistant-demo .q-chip{
  display:inline-block; background:rgba(255,255,255,0.08); border:1px solid rgba(255,255,255,0.2); color:#DCEAF2;
  padding:8px 14px; border-radius:999px; font-size:.85rem; margin:4px 6px 4px 0; cursor:pointer;
}
.assistant-demo .answer-box{
  background:rgba(255,255,255,0.06); border-radius:var(--radius-m); padding:18px; margin-top:16px; font-size:.92rem; color:#E7F0F5;
  min-height:64px;
}
.assistant-demo .answer-box .src{ display:block; margin-top:10px; font-size:.76rem; color:#9FB6C6; }

/* ---------- App 功能网格 ---------- */
.app-feature-grid{ display:grid; grid-template-columns:repeat(4,1fr); gap:16px; }
.app-feature-grid .feature{ background:var(--c-surface); border:1px solid var(--c-line); border-radius:var(--radius-m); padding:16px; text-align:center; }
.app-feature-grid .feature img{ width:44px; height:44px; margin:0 auto 10px; }
.app-feature-grid .feature h4{ font-size:.92rem; margin-bottom:4px; }
.app-feature-grid .feature p{ font-size:.8rem; color:var(--c-text-soft); margin:0; }

.download-panel{ display:grid; grid-template-columns:repeat(3,1fr); gap:18px; }
.download-panel .entry{
  background:var(--c-surface); border:1px dashed var(--c-line-strong); border-radius:var(--radius-m); padding:20px; text-align:center;
}
.download-panel .entry img{ width:56px; height:56px; margin:0 auto 12px; }
.download-panel .entry .status{ font-size:.8rem; color:var(--c-safety-deep); background:#FBEAE0; padding:4px 10px; border-radius:999px; display:inline-block; margin-top:8px; }

/* ---------- 公司介绍 / 声明 ---------- */
.notice-box{
  background:var(--c-bg-alt); border:1px solid var(--c-line); border-radius:var(--radius-m); padding:18px 22px;
  font-size:.86rem; color:var(--c-text-soft); margin-bottom:16px;
}
.notice-box strong{ color:var(--c-graphite); }

/* ---------- Footer ---------- */
.site-footer{ background:var(--c-navy-deep); color:#B9C8D3; padding:44px 0 26px; margin-top:40px; }
.footer-grid{ display:grid; grid-template-columns:1.4fr 1fr 1fr 1fr; gap:28px; margin-bottom:26px; }
.footer-grid h5{ color:#fff; font-size:.92rem; margin-bottom:12px; }
.footer-grid a{ color:#B9C8D3; display:block; font-size:.86rem; margin-bottom:8px; }
.footer-grid p{ color:#8CA1AF; font-size:.82rem; }
.footer-bottom{ border-top:1px solid rgba(255,255,255,0.1); padding-top:18px; font-size:.78rem; color:#7E93A2; display:flex; justify-content:space-between; flex-wrap:wrap; gap:8px; }
.beian-slot{ min-height:1em; }

/* ---------- 返回顶部 ---------- */
.to-top{
  position:fixed; right:18px; bottom:18px; width:44px; height:44px; border-radius:50%; background:var(--c-navy);
  color:#fff; border:none; cursor:pointer; box-shadow:var(--shadow-m); display:none; align-items:center; justify-content:center;
  font-size:1.1rem; z-index:90;
}
.to-top.show{ display:flex; }

/* ---------- 面包屑 ---------- */
.breadcrumb{ font-size:.82rem; color:var(--c-text-soft); padding:14px 0 0; }
.breadcrumb a{ color:var(--c-text-soft); }

/* ==========================================================================
   响应式
   ========================================================================== */
@media (max-width:1024px){
  .footer-grid{ grid-template-columns:1fr 1fr; }
  .app-feature-grid{ grid-template-columns:repeat(2,1fr); }
}
@media (max-width:900px){
  .hero .container{ grid-template-columns:1fr; }
  .feature-article{ grid-template-columns:1fr; }
  .feature-article .art-figure{ order:-1; }
  .rollup-grid{ grid-template-columns:1fr 1fr; }
  .download-panel{ grid-template-columns:1fr; }
}
@media (max-width:768px){
  .nav-toggle{ display:block; }
  .nav-links{
    display:none; position:absolute; top:64px; left:0; right:0; background:var(--c-bg);
    flex-direction:column; border-bottom:1px solid var(--c-line); padding:10px 20px 16px; gap:2px;
  }
  .nav-links.open{ display:flex; }
  .nav-links a{ padding:11px 8px; border-bottom:1px solid var(--c-line); border-radius:0; }
  .rollup-grid{ grid-template-columns:1fr; }
}
@media (max-width:600px){
  .hero{ padding:40px 0 46px; }
  .hero h1{ font-size:1.5rem; }
  .section{ padding:40px 0; }
  .article-full{ padding:22px; }
  .feature-article{ padding:20px; }
  .app-feature-grid{ grid-template-columns:1fr 1fr; }
  .footer-grid{ grid-template-columns:1fr; }
  .timeline{ flex-direction:column; }
  .timeline .step + .step{ border-left:1px solid var(--c-line); border-top:none; }
}