/* ==========================================================================
   道邦企服 (dbbk.cn) - 全站基础样式
   设计理念：科技蓝亮蓝 + 浅冰蓝渐变背景 + 纯白 · 专业规范
   纯原生 CSS3，无任何框架依赖
   ========================================================================== */

/* ---------- CSS 变量：科技蓝配色系统 ---------- */
:root {
  /* 纯白 / 浅蓝底 */
  --white: #FFFFFF;
  --ice-blue: #F5FAFF;
  --ice-blue-deep: #E8F3FE;
  --ice-blue-card: #FBFDFF;

  /* 科技蓝系 */
  --blue-mist: #E0F0FF;
  --blue-light: #9FD0FF;
  --blue: #3B9EFF;
  --blue-deep: #1E6FD9;
  --blue-ink: #0F4FA8;
  --blue-glow: #5BA8FF;

  /* 深蓝系 */
  --deep-blue: #0A2F5C;
  --deep-blue-2: #061E3D;

  /* 文字 */
  --ink: #0F2A4D;
  --body: #4A5C75;
  --muted: #8A9DB5;
  --faint: #B5C4D6;

  /* 功能色 */
  --accent: #FF8C42;
  --success: #22C55E;
  --border: rgba(15, 42, 77, 0.08);
  --border-strong: rgba(15, 42, 77, 0.15);
  --shadow-sm: 0 2px 12px rgba(30, 111, 217, 0.06);
  --shadow: 0 8px 32px rgba(30, 111, 217, 0.08);
  --shadow-lg: 0 16px 48px rgba(30, 111, 217, 0.12);
  --shadow-blue: 0 10px 36px rgba(30, 111, 217, 0.2);

  /* 圆角 */
  --r-sm: 8px;
  --r: 14px;
  --r-lg: 20px;
  --r-xl: 28px;

  /* 过渡 */
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);

  /* 导航高度 */
  --nav-h: 72px;
}

/* ---------- 重置 ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  font-size: 15px;
  line-height: 1.75;
  color: var(--body);
  background: var(--ice-blue);
  overflow-x: hidden;
}

img { max-width: 100%; height: auto; display: block; }

a { color: var(--blue-deep); text-decoration: none; transition: color 0.25s var(--ease); }
a:hover { color: var(--blue-ink); }

ul, ol { list-style: none; }

button { font-family: inherit; cursor: pointer; border: none; background: none; }

input, textarea, select { font-family: inherit; font-size: inherit; }

h1, h2, h3, h4, h5, h6 { color: var(--ink); font-weight: 700; line-height: 1.3; }

/* ---------- 容器 ---------- */
.container { width: 100%; max-width: 1240px; margin: 0 auto; padding: 0 28px; }
.container-sm { max-width: 880px; }
.container-lg { max-width: 1380px; }

/* ---------- 布局骨架 ---------- */
.layout { min-height: 100vh; display: flex; flex-direction: column; }
.main { flex: 1; }

/* ==========================================================================
   顶部固定导航栏 — 滚动变色 · 透明→冰蓝
   ========================================================================== */
.topbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-h);
  z-index: 1000;
  display: flex;
  align-items: center;
  transition: all 0.35s var(--ease);
  background: transparent;
}
.topbar.scrolled {
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  box-shadow: 0 1px 0 var(--border), 0 6px 28px rgba(30, 111, 217, 0.06);
}

.topbar-inner {
  width: 100%;
  max-width: 1320px;
  margin: 0 auto;
  padding: 0 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
}

/* 导航 Logo */
.nav-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}
.nav-logo img { width: 40px; height: 40px; }
.nav-logo .logo-txt { display: flex; flex-direction: column; line-height: 1.2; }
.nav-logo .logo-txt strong { font-size: 17px; color: var(--ink); letter-spacing: 0.5px; }
.nav-logo .logo-txt span { font-size: 10px; color: var(--blue-deep); letter-spacing: 1.5px; text-transform: uppercase; font-weight: 600; }

/* 主菜单 */
.nav-menu {
  display: flex;
  align-items: center;
  gap: 2px;
}
.nav-menu > li > a {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 10px 16px;
  font-size: 14.5px;
  color: var(--ink);
  border-radius: var(--r-sm);
  transition: all 0.25s var(--ease);
  position: relative;
  font-weight: 500;
}
.nav-menu > li > a:hover,
.nav-menu > li > a.active {
  color: var(--blue-deep);
  background: var(--blue-mist);
}
.nav-menu > li > a .caret {
  width: 0; height: 0;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  border-top: 5px solid currentColor;
  opacity: 0.5;
  transition: transform 0.25s var(--ease);
}
.nav-menu > li:hover > a .caret { transform: rotate(180deg); }

/* 下拉子菜单 */
.nav-menu > li { position: relative; }
.nav-sub {
  position: absolute;
  top: calc(100% + 10px);
  left: 50%;
  transform: translateX(-50%) translateY(-6px);
  min-width: 220px;
  background: var(--white);
  border-radius: var(--r);
  box-shadow: var(--shadow-lg);
  padding: 10px;
  opacity: 0;
  visibility: hidden;
  transition: all 0.28s var(--ease-out);
  border: 1px solid var(--border);
}
.nav-menu > li:hover .nav-sub {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}
.nav-sub a {
  display: block;
  padding: 10px 16px;
  font-size: 13.5px;
  color: var(--body);
  border-radius: var(--r-sm);
  transition: all 0.2s var(--ease);
}
.nav-sub a:hover { color: var(--blue-deep); background: var(--blue-mist); }

/* 导航右侧操作 */
.nav-actions { display: flex; align-items: center; gap: 14px; flex-shrink: 0; }

/* 汉堡菜单按钮 */
.hamburger {
  display: none;
  width: 42px; height: 42px;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  border-radius: var(--r-sm);
}
.hamburger span {
  display: block;
  width: 24px; height: 2.5px;
  background: var(--ink);
  border-radius: 2px;
  transition: all 0.3s var(--ease);
}
.hamburger.active span:nth-child(1) { transform: translateY(8px) rotate(45deg); }
.hamburger.active span:nth-child(2) { opacity: 0; }
.hamburger.active span:nth-child(3) { transform: translateY(-8px) rotate(-45deg); }

/* 移动端抽屉菜单 */
.mobile-drawer {
  position: fixed;
  top: 0; right: -100%;
  width: 340px;
  max-width: 88vw;
  height: 100vh;
  background: var(--white);
  z-index: 1001;
  padding: 88px 24px 32px;
  overflow-y: auto;
  transition: right 0.38s var(--ease-out);
  box-shadow: -10px 0 40px rgba(15, 42, 77, 0.15);
}
.mobile-drawer.open { right: 0; }
.mobile-drawer .m-group { margin-bottom: 6px; }
.mobile-drawer .m-group > a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 13px 16px;
  font-size: 15.5px;
  color: var(--ink);
  border-radius: var(--r-sm);
  font-weight: 600;
}
.mobile-drawer .m-group > a:hover,
.mobile-drawer .m-group > a.active { background: var(--blue-mist); color: var(--blue-deep); }
.mobile-drawer .m-sub {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.38s var(--ease);
}
.mobile-drawer .m-group.open .m-sub { max-height: 600px; }
.mobile-drawer .m-sub a {
  display: block;
  padding: 11px 16px 11px 32px;
  font-size: 14px;
  color: var(--body);
}
.mobile-drawer .m-cta {
  display: block;
  margin-top: 24px;
  padding: 15px;
  text-align: center;
  background: linear-gradient(135deg, var(--blue-deep), var(--blue-glow));
  color: var(--white);
  border-radius: var(--r);
  font-weight: 600;
  font-size: 15px;
  box-shadow: var(--shadow-blue);
}

/* 遮罩层 */
.overlay {
  position: fixed;
  inset: 0;
  background: rgba(15, 42, 77, 0.45);
  backdrop-filter: blur(4px);
  z-index: 999;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s var(--ease);
}
.overlay.show { opacity: 1; visibility: visible; }

/* ==========================================================================
   通用区块
   ========================================================================== */
.section { padding: 84px 0; position: relative; }
.section.tight { padding: 60px 0; }
.section.bg-blue { background: linear-gradient(180deg, var(--ice-blue-deep), var(--ice-blue)); }
.section.bg-white { background: var(--white); }
.section.bg-dark { background: linear-gradient(135deg, var(--deep-blue), var(--deep-blue-2)); }

/* 区块标题 */
.sec-head { text-align: center; max-width: 700px; margin: 0 auto 52px; }
.sec-head .eyebrow {
  display: inline-block;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 2.5px;
  text-transform: uppercase;
  color: var(--blue-deep);
  background: var(--blue-mist);
  padding: 6px 16px;
  border-radius: 24px;
  margin-bottom: 18px;
}
.sec-head h2 { font-size: 34px; margin-bottom: 14px; letter-spacing: -0.3px; }
.sec-head h2 .accent { color: var(--blue-deep); }
.sec-head p { font-size: 15.5px; color: var(--muted); }

/* ---------- 独立通用元素（在非 sec-head 下也生效）---------- */
.eyebrow {
  display: inline-block;
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: 2.5px;
  text-transform: uppercase;
  color: var(--blue-deep);
  background: var(--blue-mist);
  padding: 6px 16px;
  border-radius: 24px;
  margin-bottom: 18px;
}
.accent { color: var(--blue-deep); }
.lead {
  font-size: 16.5px;
  line-height: 1.8;
  color: var(--text);
  margin-bottom: 22px;
}
.lead strong { color: var(--ink); font-weight: 600; }

/* 虚化装饰球 */
.blur-deco {
  position: absolute;
  pointer-events: none;
  z-index: 0;
  border-radius: 50%;
  filter: blur(70px);
  opacity: 0.45;
}
.blur-deco.b1 { width: 400px; height: 400px; background: var(--blue-light); bottom: -100px; left: -100px; }
.blur-deco.b2 { width: 340px; height: 340px; background: #B8DAFF; top: -80px; right: -60px; }
.blur-deco.b3 { width: 280px; height: 280px; background: var(--blue-mist); top: 10%; right: -120px; }
.section > .container { position: relative; z-index: 1; }

/* ==========================================================================
   统一页脚
   ========================================================================== */
.site-foot {
  background: linear-gradient(135deg, var(--deep-blue) 0%, var(--deep-blue-2) 100%);
  color: rgba(255, 255, 255, 0.7);
  padding: 72px 0 0;
  position: relative;
  overflow: hidden;
}
.site-foot::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--blue-glow), var(--blue), var(--blue-glow));
}
.site-foot::after {
  content: "";
  position: absolute;
  width: 500px; height: 500px;
  background: var(--blue-deep);
  border-radius: 50%;
  filter: blur(120px);
  opacity: 0.15;
  bottom: -180px; right: -120px;
  pointer-events: none;
}
.foot-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1.2fr;
  gap: 48px;
  margin-bottom: 52px;
}
.foot-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 18px;
}
.foot-brand img { width: 40px; height: 40px; }
.foot-brand strong { color: var(--white); font-size: 18px; }
.foot-col p { font-size: 13.5px; line-height: 1.85; }
.foot-col h4 {
  color: var(--white);
  font-size: 15.5px;
  margin-bottom: 20px;
  position: relative;
  padding-left: 16px;
}
.foot-col h4::before {
  content: "";
  position: absolute;
  left: 0; top: 50%;
  transform: translateY(-50%);
  width: 4px; height: 18px;
  background: linear-gradient(180deg, var(--blue-glow), var(--blue-deep));
  border-radius: 2px;
}
.foot-col ul li { margin-bottom: 11px; }
.foot-col ul li a { font-size: 13.5px; color: rgba(255, 255, 255, 0.6); transition: all 0.2s var(--ease); }
.foot-col ul li a:hover { color: var(--blue-glow); padding-left: 4px; }
.foot-contact li { display: flex; align-items: flex-start; gap: 12px; font-size: 13.5px; margin-bottom: 14px; }
.foot-contact li svg { flex-shrink: 0; margin-top: 3px; color: var(--blue-glow); }

.foot-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding: 26px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.foot-bottom p { font-size: 13px; color: rgba(255, 255, 255, 0.5); }
.foot-links { display: flex; gap: 22px; }
.foot-links a { font-size: 13px; color: rgba(255, 255, 255, 0.5); }
.foot-links a:hover { color: var(--blue-glow); }

/* ==========================================================================
   滚动渐入动画
   ========================================================================== */
.reveal {
  opacity: 0;
  transform: translateY(32px);
  transition: opacity 0.75s var(--ease-out), transform 0.75s var(--ease-out);
}
.reveal.in { opacity: 1; transform: translateY(0); }
.reveal.d1 { transition-delay: 0.1s; }
.reveal.d2 { transition-delay: 0.2s; }
.reveal.d3 { transition-delay: 0.3s; }
.reveal.d4 { transition-delay: 0.4s; }
.reveal.d5 { transition-delay: 0.5s; }

/* 返回顶部 */
.back-top {
  position: fixed;
  bottom: 36px; right: 36px;
  width: 52px; height: 52px;
  display: flex; align-items: center; justify-content: center;
  background: var(--white);
  border-radius: 50%;
  box-shadow: var(--shadow-lg);
  color: var(--blue-deep);
  z-index: 900;
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all 0.3s var(--ease);
}
.back-top.show { opacity: 1; visibility: visible; transform: translateY(0); }
.back-top:hover { background: var(--blue-deep); color: var(--white); transform: translateY(-2px); box-shadow: var(--shadow-blue); }

/* ==========================================================================
   响应式
   ========================================================================== */
@media (max-width: 1024px) {
  .foot-grid { grid-template-columns: 1fr 1fr; gap: 36px; }
}

@media (max-width: 900px) {
  .nav-menu { display: none; }
  .hamburger { display: flex; }
  .section { padding: 60px 0; }
  .sec-head h2 { font-size: 27px; }
  .sec-head { margin-bottom: 40px; }
}

@media (max-width: 640px) {
  .container { padding: 0 18px; }
  .topbar-inner { padding: 0 18px; }
  .nav-logo .logo-txt span { display: none; }
  .section { padding: 48px 0; }
  .sec-head h2 { font-size: 24px; }
  .foot-grid { grid-template-columns: 1fr; gap: 32px; }
  .foot-bottom { flex-direction: column; text-align: center; }
  .back-top { bottom: 24px; right: 24px; width: 46px; height: 46px; }
}

/* 选中文本配色 */
::selection { background: var(--blue-light); color: var(--ink); }

/* 滚动条 */
::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-track { background: var(--ice-blue-deep); }
::-webkit-scrollbar-thumb { background: var(--blue-light); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: var(--blue); }