/* BD 子站 — 与官网中文首页同源色板与字体 */
:root {
  --consun-900: #005F72;
  --consun-800: #007387;
  --consun-700: #008AA4;
  --consun-600: #0098B5;
  --consun-500: #41A9BC;
  --consun-400: #5DBACE;
  --consun-300: #81CCD9;
  --consun-200: #B0F2F4;
  --consun-100: #D6F2F7;
  --consun-50: #EDF9FB;
  --gold-500: #C9982E;
  --gold-400: #D4AD4E;
  --gold-300: #E0C273;
  --slate-900: #0F172A;
  --slate-800: #1E293B;
  --slate-700: #334155;
  --slate-600: #475569;
  --slate-500: #64748B;
  --slate-400: #94A3B8;
  --slate-300: #CBD5E1;
  --slate-200: #E2E8F0;
  --slate-100: #F1F5F9;
  --slate-50: #F8FAFC;
  --white: #FFFFFF;
  --font-display: 'Fraunces', 'Songti SC', 'STSong', 'SimSun', Georgia, serif;
  --font-body: 'DM Sans', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei UI', 'Microsoft YaHei', sans-serif;
  /* 与顶栏、横幅、正文统一左右留白，便于上下对齐 */
  --bd-page-max: 1240px;
  --bd-gutter: 32px;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--slate-800);
  background: var(--slate-50);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

/* —— 顶栏 —— */
.bd-head {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--white);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.04);
}
.bd-head-inner {
  max-width: var(--bd-page-max);
  margin: 0 auto;
  padding: 14px var(--bd-gutter);
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: 12px 28px;
  flex-wrap: wrap;
}
.bd-logo {
  display: block;
  height: 40px;
  width: auto;
}
.bd-head-nav {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
}
.bd-head-nav a {
  display: inline-flex;
  align-items: center;
  padding: 8px 14px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  color: var(--slate-700);
  text-decoration: none;
  transition: background 0.2s, color 0.2s;
  white-space: nowrap;
}
.bd-head-nav a:hover {
  background: var(--consun-50);
  color: var(--consun-700);
}

/* —— 横幅 —— */
.bd-banner {
  background: linear-gradient(135deg, #004D5E 0%, var(--consun-800) 50%, var(--consun-700) 100%);
  color: var(--white);
  position: relative;
  overflow: hidden;
}
.bd-banner::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(circle at 10% 40%, rgba(201, 152, 46, 0.1) 0%, transparent 45%),
    radial-gradient(circle at 90% 60%, rgba(176, 242, 244, 0.08) 0%, transparent 50%);
  pointer-events: none;
}
.bd-banner-inner {
  position: relative;
  max-width: var(--bd-page-max);
  margin: 0 auto;
  padding: 44px var(--bd-gutter) 48px;
}
.bd-banner-kicker {
  font-size: 13px;
  color: rgba(230, 248, 252, 0.85);
  margin: 0 0 16px;
  letter-spacing: 0.02em;
}
.bd-banner-kicker a {
  color: inherit;
  text-decoration: none;
  border-bottom: 1px solid rgba(255, 255, 255, 0.25);
  transition: border-color 0.2s, color 0.2s;
}
.bd-banner-kicker a:hover {
  color: var(--white);
  border-bottom-color: rgba(255, 255, 255, 0.55);
}
.bd-banner h1 {
  font-family: var(--font-display);
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 600;
  letter-spacing: 0.02em;
  line-height: 1.2;
  margin: 0;
}

/* —— 正文区（与顶栏、横幅同宽，减少大屏两侧空白） —— */
.bd-main {
  max-width: var(--bd-page-max);
  margin: 0 auto;
  padding: 48px var(--bd-gutter) 72px;
}
.bd-prose {
  width: 100%;
  max-width: none;
  margin: 0;
  background: var(--white);
  border-radius: 16px;
  padding: 40px clamp(24px, 4vw, 56px) 48px;
  border: 1px solid var(--slate-200);
  box-shadow:
    0 4px 24px rgba(15, 23, 42, 0.06),
    0 1px 3px rgba(15, 23, 42, 0.04);
}
.bd-prose .lead {
  font-size: 17px;
  line-height: 1.75;
  color: var(--slate-700);
  margin: 0 0 32px;
  padding-bottom: 28px;
  border-bottom: 1px solid var(--slate-100);
}
.bd-prose .lead strong { color: var(--consun-800); }
.bd-prose h2 {
  font-family: var(--font-display);
  font-size: 1.35rem;
  font-weight: 600;
  color: var(--consun-900);
  letter-spacing: 0.02em;
  margin: 40px 0 16px;
  line-height: 1.35;
}
.bd-prose h2:first-of-type { margin-top: 0; }
.bd-prose h3 {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--slate-800);
  margin: 28px 0 10px;
  letter-spacing: 0.02em;
}
.bd-prose p {
  margin: 0 0 14px;
  font-size: 15px;
  color: var(--slate-700);
  line-height: 1.8;
}
.bd-prose ul {
  margin: 12px 0 20px;
  padding-left: 1.25em;
}
.bd-prose li {
  margin-bottom: 10px;
  font-size: 15px;
  color: var(--slate-700);
  line-height: 1.75;
}
.bd-prose a {
  color: var(--consun-700);
  font-weight: 600;
  text-decoration: none;
  border-bottom: 1px solid rgba(0, 138, 164, 0.35);
  transition: color 0.2s, border-color 0.2s;
}
.bd-prose a:hover {
  color: var(--consun-800);
  border-bottom-color: var(--consun-600);
}
.bd-callout {
  margin-top: 24px;
  padding: 20px 22px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--consun-50) 0%, rgba(237, 249, 251, 0.6) 100%);
  border-left: 4px solid var(--gold-400);
  font-size: 15px;
  font-weight: 500;
  color: var(--slate-800);
  line-height: 1.7;
}

/* —— 页脚 —— */
.bd-foot {
  background: var(--slate-900);
  color: var(--slate-400);
  text-align: center;
  padding: 32px 24px 40px;
  font-size: 14px;
}
.bd-foot p { margin: 0; line-height: 1.6; }
.bd-foot a {
  color: var(--consun-300);
  text-decoration: none;
}
.bd-foot a:hover { color: var(--consun-200); text-decoration: underline; }

/* —— 语言入口 hub（bd/index.html）—— */
.bd-hub {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 48px 24px;
  background: linear-gradient(160deg, var(--slate-50) 0%, var(--consun-50) 45%, var(--white) 100%);
}
.bd-hub-main {
  max-width: 480px;
  text-align: center;
  background: var(--white);
  padding: 48px 40px 44px;
  border-radius: 20px;
  border: 1px solid var(--slate-200);
  box-shadow: 0 12px 40px rgba(15, 23, 42, 0.08);
}
.bd-hub-logo {
  margin: 0 auto 28px;
  display: block;
}
.bd-hub-main h1 {
  font-family: var(--font-display);
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--consun-900);
  margin: 0 0 16px;
  letter-spacing: 0.02em;
}
.bd-hub-sub {
  font-size: 15px;
  color: var(--slate-600);
  line-height: 1.7;
  margin: 0 0 28px;
  text-align: left;
}
.bd-hub-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin-bottom: 24px;
}
.bd-hub-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 28px;
  border-radius: 10px;
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  color: var(--slate-700);
  background: var(--slate-100);
  border: 1px solid var(--slate-200);
  transition: background 0.2s, border-color 0.2s, color 0.2s;
}
.bd-hub-btn:hover {
  background: var(--slate-200);
  color: var(--slate-900);
}
.bd-hub-btn-primary {
  background: var(--consun-700);
  color: var(--white);
  border-color: var(--consun-700);
}
.bd-hub-btn-primary:hover {
  background: var(--consun-800);
  border-color: var(--consun-800);
  color: var(--white);
}
.bd-hub-back {
  margin: 0;
  font-size: 14px;
  color: var(--slate-500);
}
.bd-hub-back a {
  color: var(--consun-700);
  text-decoration: none;
  font-weight: 500;
}
.bd-hub-back a:hover { text-decoration: underline; }

@media (max-width: 768px) {
  :root { --bd-gutter: 20px; }
  .bd-head-inner { padding: 12px var(--bd-gutter); }
  .bd-head-nav { width: 100%; justify-content: flex-start; }
  .bd-banner-inner { padding: 36px var(--bd-gutter) 40px; }
  .bd-main { padding: 32px var(--bd-gutter) 56px; }
  .bd-prose { padding: 28px 22px 36px; border-radius: 12px; }
  .bd-prose h2 { font-size: 1.2rem; margin-top: 32px; }
}