/* ============================================================
   kc.bjgov.cn · 首届科创和AI创新博览会官网
   设计系统 v2.0 · 浅色国际化（WAIC / Apple / Stripe 级）
   浅蓝白底 + 科技蓝 + 金色院士点缀 · 响应式
   ============================================================ */

:root {
  /* 色板 · 浅色国际 */
  --bg: #F4F7FE;               /* 浅蓝白主背景 */
  --bg-alt: #FFFFFF;           /* 白区块 */
  --bg-soft: #EDF2FC;          /* 浅蓝灰分区 */
  --card: #FFFFFF;
  --card-soft: #F8FAFF;
  --blue: #2563EB;             /* 科技蓝主色 */
  --blue-bright: #3B82F6;
  --cyan: #0891B2;             /* 深青 · AI 感（浅底用深色） */
  --cyan-light: #06B6D4;
  --purple: #7C3AED;             /* 紫罗兰 · WAIC式高级感 */
  --purple-light: #A78BFA;
  --violet: #4F46E5;             /* 靛蓝紫 */
  --grad-brand: linear-gradient(93deg, #2563EB 0%, #7C3AED 55%, #0EA5E9 100%);  /* 品牌三色渐变·WebSummit式对角 */
  --grad-brand-size: 130% 130%;
  --grad-brand-h: linear-gradient(90deg, #2563EB 0%, #7C3AED 60%, #06B6D4 120%);  /* 横向版 */
  --grad-soft: linear-gradient(135deg, rgba(37,99,235,0.10), rgba(124,58,237,0.10), rgba(6,182,212,0.10));  /* 柔和渐变 */
  --gold: #B8860B;             /* 深金 · 浅底可读 */
  --gold-bright: #D4A017;
  --text-1: #0E1628;           /* 标题 */
  --text-2: #3B4A63;           /* 正文 */
  --text-3: #7C88A3;           /* 次要 */
  --line: #E2E8F4;
  --line-bright: rgba(37, 99, 235, 0.35);

  /* 圆角 */
  --r-sm: 10px;
  --r-md: 16px;
  --r-lg: 24px;
  --r-pill: 999px;

  /* 字体 */
  --font-cn: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", -apple-system, sans-serif;
  --font-en: "Helvetica Neue", "Inter", "SF Pro Display", system-ui, sans-serif;
  --font-num: "SF Mono", "JetBrains Mono", Menlo, monospace;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-cn);
  background: var(--bg);
  color: var(--text-2);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* ---------- 背景氛围 · 浅色 ---------- */
.bg-atmosphere {
  position: fixed; inset: 0; z-index: -2;
  background:
    radial-gradient(ellipse 70% 50% at 15% -10%, rgba(37, 99, 235, 0.10), transparent 60%),
    radial-gradient(ellipse 50% 40% at 90% 10%, rgba(6, 182, 212, 0.07), transparent 60%),
    radial-gradient(ellipse 45% 40% at 65% 40%, rgba(124, 58, 237, 0.06), transparent 60%),
    radial-gradient(ellipse 55% 45% at 80% 90%, rgba(201, 169, 110, 0.08), transparent 60%),
    var(--bg);
}
.bg-grid {
  position: fixed; inset: 0; z-index: -1;
  background-image:
    linear-gradient(rgba(37, 99, 235, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(37, 99, 235, 0.035) 1px, transparent 1px);
  background-size: 56px 56px;
  mask-image: radial-gradient(ellipse 90% 70% at 50% 0%, black 40%, transparent 100%);
  -webkit-mask-image: radial-gradient(ellipse 90% 70% at 50% 0%, black 40%, transparent 100%);
  pointer-events: none;
}

.container { max-width: 1280px; margin: 0 auto; padding: 0 32px; }

/* ---------- 公告条 ---------- */
.announce {
  background: linear-gradient(90deg, #1E40AF, #2563EB);
  color: #fff;
  font-size: 13.5px;
  text-align: center;
  padding: 9px 16px;
  letter-spacing: 0.5px;
}
.announce a { color: #FDE68A; text-decoration: none; font-weight: 600; margin-left: 6px; }
.announce a:hover { text-decoration: underline; }

/* ---------- 导航 ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: 72px;
  display: flex;
  align-items: center;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--line);
}
.nav-inner {
  width: 100%; max-width: 1280px; margin: 0 auto; padding: 0 32px;
  display: flex; align-items: center; gap: 40px;
}
.logo { display: flex; align-items: center; gap: 12px; text-decoration: none; flex-shrink: 0; }
.logo-mark {
  width: 38px; height: 38px; border-radius: 12px;
  background: linear-gradient(135deg, var(--blue), var(--cyan-light));
  display: flex; align-items: center; justify-content: center;
  font-weight: 800; font-size: 17px; color: #fff;
  box-shadow: 0 4px 16px rgba(37, 99, 235, 0.3);
}
.logo-text { display: flex; flex-direction: column; line-height: 1.2; }
.logo-text .cn { font-size: 15px; font-weight: 700; letter-spacing: 1px; color: var(--text-1); }
.logo-text .en { font-size: 9px; letter-spacing: 2.5px; color: var(--text-3); text-transform: uppercase; }

.nav-links { display: flex; align-items: center; gap: 2px; margin-left: auto; list-style: none; }
.nav-links a {
  display: block; padding: 9px 15px;
  color: var(--text-2); text-decoration: none; font-size: 14.5px; font-weight: 500;
  border-radius: 8px; transition: color 0.2s, background 0.2s; white-space: nowrap;
}
.nav-links a:hover { color: var(--blue); background: rgba(37, 99, 235, 0.07); }
.nav-links a.active { color: var(--blue); background: rgba(37, 99, 235, 0.1); font-weight: 600; }
.nav-cta {
  margin-left: 8px; padding: 10px 24px; border-radius: var(--r-pill);
  background: var(--grad-brand); background-size: var(--grad-brand-size);
  color: #fff !important; font-weight: 600;
  box-shadow: 0 4px 18px rgba(37, 99, 235, 0.35);
  transition: transform 0.2s, box-shadow 0.2s, background-position 3s ease;
}
.nav-cta:hover { transform: translateY(-1px); box-shadow: 0 8px 26px rgba(37, 99, 235, 0.45); background-position: 100% 50%; }

.nav-toggle { display: none; background: none; border: none; cursor: pointer; padding: 8px; }
.nav-toggle span { display: block; width: 22px; height: 2px; background: var(--text-1); margin: 5px 0; border-radius: 2px; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 13px 30px; border-radius: var(--r-pill);
  font-size: 15px; font-weight: 600; text-decoration: none;
  border: none; cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s, background 0.2s; white-space: nowrap;
}
.btn-primary { background: var(--grad-brand); background-size: var(--grad-brand-size); color: #fff; box-shadow: 0 6px 22px rgba(37, 99, 235, 0.35); transition: transform 0.2s, box-shadow 0.2s, background-position 3s ease; }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 10px 30px rgba(37, 99, 235, 0.45); background-position: 100% 50%; }
.btn-gold { background: linear-gradient(135deg, #B8860B, #D4A017); color: #fff; box-shadow: 0 6px 22px rgba(184, 134, 11, 0.3); }
.btn-gold:hover { transform: translateY(-2px); box-shadow: 0 10px 30px rgba(184, 134, 11, 0.4); }
.btn-ghost { background: #fff; color: var(--blue); border: 1.5px solid var(--blue-bright); }
.btn-ghost:hover { background: rgba(37, 99, 235, 0.06); transform: translateY(-2px); }

/* ---------- 区块 ---------- */
.section { padding: 96px 0; position: relative; }
.section-tight { padding: 72px 0; }
.section-white { background: var(--bg-alt); }
.sec-head { max-width: 760px; margin-bottom: 52px; }
.sec-head.center { margin-left: auto; margin-right: auto; text-align: center; }
.sec-kicker {
  font-family: var(--font-en); font-size: 12px; font-weight: 700;
  letter-spacing: 4px; text-transform: uppercase; color: var(--blue);
  margin-bottom: 14px;
}
.sec-kicker.gold { color: var(--gold); }
.sec-title { font-size: clamp(28px, 4vw, 42px); font-weight: 800; letter-spacing: -0.5px; line-height: 1.2; color: var(--text-1); margin-bottom: 16px; }
.sec-title .grad { background: var(--grad-brand-h); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.sec-title .gold-grad { background: linear-gradient(90deg, #B8860B, #D4A017); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.sec-desc { font-size: 16px; color: var(--text-2); line-height: 1.9; }

/* ---------- 卡片 ---------- */
.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  padding: 28px;
  box-shadow: 0 1px 3px rgba(14, 22, 40, 0.04);
  transition: transform 0.3s, box-shadow 0.3s, border-color 0.3s;
}
.card:hover { transform: translateY(-4px); box-shadow: 0 20px 48px rgba(14, 22, 40, 0.12), 0 4px 12px rgba(124, 58, 237, 0.06); border-color: rgba(124, 58, 237, 0.25); }
.card .card-icon {
  width: 46px; height: 46px; border-radius: 13px;
  background: var(--grad-soft);
  border: 1px solid rgba(124, 58, 237, 0.2);
  display: flex; align-items: center; justify-content: center;
  font-size: 20px; margin-bottom: 18px; color: var(--purple);
}
.card h3 { font-size: 19px; font-weight: 700; color: var(--text-1); margin-bottom: 10px; }
.card p { font-size: 14px; color: var(--text-2); line-height: 1.75; }

/* ---------- 数字大字报 ---------- */
.stat-row { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.stat {
  text-align: center; padding: 36px 20px;
  border-radius: var(--r-md);
  background: var(--card); border: 1px solid var(--line);
  box-shadow: 0 1px 3px rgba(14, 22, 40, 0.04);
  position: relative; overflow: hidden;
}
.stat::before { content: ''; position: absolute; top: 0; left: 20%; right: 20%; height: 3px; background: linear-gradient(90deg, transparent, #7C3AED, #06B6D4, transparent); }
.stat .num { font-family: var(--font-num); font-size: clamp(36px, 5vw, 54px); font-weight: 800; letter-spacing: -1px; background: var(--grad-brand-h); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; line-height: 1.1; }
.stat .num small { font-size: 0.45em; margin-left: 2px; color: var(--gold); }
.stat .lbl { margin-top: 10px; font-size: 14px; color: var(--text-3); letter-spacing: 1px; }

/* ---------- 倒计时 ---------- */
.countdown { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.cd-item { min-width: 88px; padding: 18px 12px; border-radius: var(--r-md); background: var(--card-soft); border: 1px solid var(--line); text-align: center; }
.cd-item .n { font-family: var(--font-num); font-size: 38px; font-weight: 800; background: var(--grad-brand-h); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; line-height: 1.1; }
.cd-item .u { font-size: 12px; color: var(--text-3); margin-top: 6px; letter-spacing: 2px; }

/* ---------- 表单焦点光环（WebSummit式：1px白+3px浅蓝双层） ---------- */
input:focus, textarea:focus, select:focus {
  outline: none;
  box-shadow: 0 0 0 1px #fff, 0 0 0 3px rgba(165, 196, 227, 0.9);
  border-color: rgba(37, 99, 235, 0.5) !important;
  transition: box-shadow 0.25s ease, border-color 0.25s ease;
}

/* ---------- 页脚 ---------- */
.footer { border-top: 1px solid var(--line); padding: 64px 0 40px; background: #0B1220; color: var(--text-3); }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 48px; }
.footer h4 { font-size: 14px; color: #E8EDF8; margin-bottom: 16px; letter-spacing: 1px; }
.footer ul { list-style: none; }
.footer ul li { margin-bottom: 10px; }
.footer ul a { color: #8A94AB; text-decoration: none; font-size: 13.5px; transition: color 0.2s; }
.footer ul a:hover { color: #6FB3FF; }
.footer .about { font-size: 13.5px; color: #8A94AB; line-height: 1.9; }
.footer .about b { color: #B9C4DC; }
.footer .logo-text .cn { color: #fff; }
.footer .logo-text .en { color: #6B768E; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,0.08); padding-top: 28px; display: flex; justify-content: space-between; align-items: center; gap: 16px; flex-wrap: wrap; font-size: 13px; color: #6B768E; }
.footer-bottom a { color: #6B768E; text-decoration: none; }

/* ---------- 页面内部 hero ---------- */
.page-hero {
  padding: 72px 0 60px;
  position: relative;
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(ellipse 60% 70% at 80% 0%, rgba(37, 99, 235, 0.08), transparent 60%),
    radial-gradient(ellipse 40% 50% at 10% 100%, rgba(201, 169, 110, 0.06), transparent 60%);
}
.page-hero .crumb { font-size: 13px; color: var(--text-3); margin-bottom: 16px; letter-spacing: 1px; }
.page-hero .crumb a { color: var(--text-3); text-decoration: none; }
.page-hero .crumb a:hover { color: var(--blue); }
.page-hero h1 { font-size: clamp(32px, 5vw, 52px); font-weight: 800; letter-spacing: -0.5px; line-height: 1.15; color: var(--text-1); margin-bottom: 16px; }
.page-hero .lead { font-size: 17px; color: var(--text-2); max-width: 660px; line-height: 1.9; }

/* ---------- 响应式 ---------- */
@media (max-width: 1024px) {
  .nav-links { display: none; }
  .nav-toggle { display: block; }
  .nav-links.open {
    display: flex; position: fixed; top: 72px; left: 0; right: 0;
    flex-direction: column; background: #fff; padding: 16px 24px; gap: 4px;
    border-bottom: 1px solid var(--line); box-shadow: 0 20px 40px rgba(14,22,40,0.12);
  }
  .nav-links.open a { width: 100%; }
  .stat-row { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 640px) {
  .container { padding: 0 20px; }
  .stat-row { grid-template-columns: 1fr 1fr; gap: 12px; }
  .section { padding: 64px 0; }
  .footer-grid { grid-template-columns: 1fr; }
  .announce { font-size: 12px; }
}

/* ---------- 动效 ---------- */
@keyframes fadeUp { from { opacity: 0; transform: translateY(28px); } to { opacity: 1; transform: translateY(0); } }
@keyframes floatY { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-14px); } }
.reveal { opacity: 0; }
.reveal.visible { animation: fadeUp 0.8s cubic-bezier(0.16, 1, 0.3, 1) forwards; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; }
  * { animation: none !important; transition: none !important; }
}

/* ---------- 卖点跑马灯（Slush式 #标签） ---------- */
.marquee { overflow: hidden; background: linear-gradient(90deg, rgba(37,99,235,0.05), rgba(124,58,237,0.05), rgba(6,182,212,0.05)); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); padding: 16px 0; }
.marquee-track { display: flex; gap: 40px; white-space: nowrap; animation: marqueeScroll 30s linear infinite; width: max-content; }
.marquee-track span { font-family: var(--font-num); font-size: 14px; font-weight: 600; letter-spacing: 1px; color: var(--text-2); }
.marquee-track span b { color: var(--purple); }
@keyframes marqueeScroll { from { transform: translateX(0); } to { transform: translateX(-50%); } }
@media (prefers-reduced-motion: reduce) { .marquee-track { animation: none; flex-wrap: wrap; } }

/* ---------- 数据胶囊（SXSW式声明式） ---------- */
.data-pills { display: flex; gap: 14px; flex-wrap: wrap; justify-content: center; }
.data-pill { display: inline-flex; align-items: center; gap: 10px; padding: 12px 22px; border-radius: var(--r-pill); background: var(--card); border: 1px solid var(--line); font-size: 14.5px; font-weight: 600; color: var(--text-1); box-shadow: 0 2px 10px rgba(14,22,40,0.04); }
.data-pill .d-ic { font-size: 17px; }
.data-pill .d-num { font-family: var(--font-num); font-weight: 800; color: var(--purple); }
.data-pill .d-lbl { color: var(--text-3); font-weight: 500; }