/* ==========================================================================
   北京尧图网络科技 - 全站基础样式
   风格：窗帘治愈风 · 奶白 + 浅蓝 + 浅绿
   布局：弧形圆角包裹布局 · 顶部固定导航
   ========================================================================== */

/* ---------- 设计变量 ---------- */
:root {
  /* 奶白系 - 主背景 */
  --cream: #FBFCFA;
  --cream-2: #F4F7F2;
  --cream-3: #EDF2EE;

  /* 浅蓝系 - 主色调 */
  --blue: #8FC1DB;
  --blue-deep: #5B95B8;
  --blue-ink: #3A6B85;
  --blue-soft: #D4E9F2;
  --blue-mist: #E8F2F7;

  /* 浅绿系 - 辅助色 */
  --green: #A8D8B9;
  --green-deep: #6FAE85;
  --green-soft: #DCEEDF;
  --green-mist: #EEF7F0;

  /* 中性文字 */
  --ink: #2B3D4F;
  --body: #4A5C6E;
  --muted: #8B9DAA;
  --line: #DDE6E0;
  --white: #ffffff;

  /* 阴影 */
  --shadow-sm: 0 2px 12px rgba(91, 149, 184, 0.06);
  --shadow-md: 0 8px 30px rgba(91, 149, 184, 0.10);
  --shadow-lg: 0 20px 50px rgba(91, 149, 184, 0.14);
  --shadow-arc: 0 4px 24px rgba(111, 174, 133, 0.08);

  /* 圆角 */
  --r-sm: 12px;
  --r-md: 20px;
  --r-lg: 32px;
  --r-xl: 48px;
  --r-pill: 999px;

  /* 布局尺寸 */
  --nav-h: 72px;
  --main-max: 1280px;

  /* 字体 */
  --font: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-en: "Georgia", "Times New Roman", serif;
}

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

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

body {
  font-family: var(--font);
  color: var(--body);
  background: var(--cream);
  line-height: 1.75;
  font-size: 15px;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: var(--blue-ink);
  text-decoration: none;
  transition: color 0.3s ease;
}

a:hover {
  color: var(--green-deep);
}

ul,
ol {
  list-style: none;
}

h1, h2, h3, h4, h5, h6 {
  color: var(--ink);
  font-weight: 700;
  line-height: 1.35;
}

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

::selection {
  background: var(--blue-soft);
  color: var(--blue-ink);
}

/* ==========================================================================
   顶部固定导航栏
   ========================================================================== */
.top-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-h);
  background: rgba(251, 252, 250, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid transparent;
  z-index: 1000;
  transition: all 0.35s ease;
}

.top-nav.scrolled {
  background: rgba(251, 252, 250, 0.95);
  border-bottom-color: var(--line);
  box-shadow: var(--shadow-sm);
}

.nav-inner {
  max-width: var(--main-max);
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 40px;
}

/* Logo */
.nav-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

.nav-logo .logo-mark {
  width: 42px;
  height: 42px;
  flex-shrink: 0;
}

.nav-logo .logo-text {
  display: flex;
  flex-direction: column;
}

.nav-logo .logo-text strong {
  font-size: 19px;
  color: var(--ink);
  letter-spacing: 1px;
}

.nav-logo .logo-text span {
  font-size: 10.5px;
  color: var(--blue-deep);
  letter-spacing: 2.5px;
  text-transform: uppercase;
  font-family: var(--font-en);
}

/* 导航菜单 */
.nav-menu {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-menu > .nav-item {
  position: relative;
}

.nav-menu > .nav-item > a {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 10px 18px;
  border-radius: var(--r-pill);
  color: var(--body);
  font-size: 14.5px;
  font-weight: 500;
  transition: all 0.28s ease;
}

.nav-menu > .nav-item > a:hover {
  background: var(--blue-mist);
  color: var(--blue-ink);
}

.nav-menu > .nav-item.active > a {
  background: linear-gradient(135deg, var(--blue) 0%, var(--blue-deep) 100%);
  color: #fff;
}

/* 下拉菜单 */
.nav-dropdown {
  position: absolute;
  top: calc(100% + 12px);
  left: 50%;
  transform: translateX(-50%) translateY(-8px);
  background: #fff;
  border-radius: var(--r-md);
  box-shadow: var(--shadow-lg);
  padding: 12px;
  min-width: 200px;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  border: 1px solid var(--line);
}

.nav-item:hover .nav-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

.nav-dropdown a {
  display: block;
  padding: 9px 16px;
  border-radius: var(--r-sm);
  font-size: 13.5px;
  color: var(--body);
  transition: all 0.2s ease;
}

.nav-dropdown a:hover {
  background: var(--green-mist);
  color: var(--green-deep);
  padding-left: 20px;
}

/* 导航 CTA */
.nav-cta {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 24px;
  border-radius: var(--r-pill);
  background: linear-gradient(135deg, var(--green) 0%, var(--green-deep) 100%);
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  box-shadow: var(--shadow-sm);
  transition: all 0.3s ease;
  flex-shrink: 0;
}

.nav-cta:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  color: #fff;
}

/* 汉堡菜单按钮 */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 8px;
}

.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--ink);
  border-radius: 2px;
  transition: all 0.3s ease;
}

.hamburger.active span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.hamburger.active span:nth-child(2) {
  opacity: 0;
}
.hamburger.active span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* 移动端遮罩 */
.nav-overlay {
  position: fixed;
  inset: 0;
  background: rgba(43, 61, 79, 0.4);
  backdrop-filter: blur(4px);
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  z-index: 998;
}

.nav-overlay.show {
  opacity: 1;
  visibility: visible;
}

/* ==========================================================================
   通用组件
   ========================================================================== */

/* ---------- 容器 ---------- */
.container {
  width: 100%;
  max-width: var(--main-max);
  margin: 0 auto;
  padding: 0 40px;
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 13px 32px;
  border-radius: var(--r-pill);
  font-size: 14.5px;
  font-weight: 600;
  transition: all 0.3s ease;
  cursor: pointer;
  letter-spacing: 0.5px;
}

.btn-primary {
  background: linear-gradient(135deg, var(--blue) 0%, var(--blue-deep) 100%);
  color: #fff;
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  color: #fff;
}

.btn-green {
  background: linear-gradient(135deg, var(--green) 0%, var(--green-deep) 100%);
  color: #fff;
  box-shadow: var(--shadow-sm);
}

.btn-green:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  color: #fff;
}

.btn-ghost {
  background: transparent;
  color: var(--blue-ink);
  border: 1.5px solid var(--blue);
}

.btn-ghost:hover {
  background: var(--blue-deep);
  color: #fff;
  border-color: var(--blue-deep);
}

/* ---------- 区块标题 ---------- */
.sec-head {
  text-align: center;
  max-width: 740px;
  margin: 0 auto 56px;
}

.sec-head .eyebrow {
  display: inline-block;
  font-size: 12px;
  letter-spacing: 4px;
  color: var(--green-deep);
  text-transform: uppercase;
  font-family: var(--font-en);
  margin-bottom: 14px;
  padding: 5px 18px;
  background: var(--green-soft);
  border-radius: var(--r-pill);
}

.sec-head h2 {
  font-size: 38px;
  color: var(--ink);
  margin-bottom: 16px;
  letter-spacing: 1px;
}

.sec-head h2 .accent {
  color: var(--blue-deep);
  position: relative;
}

.sec-head h2 .accent::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 2px;
  width: 100%;
  height: 8px;
  background: var(--blue-soft);
  z-index: -1;
  border-radius: 4px;
}

.sec-head p {
  color: var(--muted);
  font-size: 15.5px;
}

.sec-head.left {
  text-align: left;
  margin-left: 0;
}

/* ---------- 通用 section ---------- */
.section {
  padding: 90px 0;
}

.section.tight {
  padding: 60px 0;
}

/* 弧形背景包裹 */
.bg-cream {
  background: var(--cream-2);
}

.bg-blue {
  background: linear-gradient(180deg, var(--blue-mist) 0%, var(--cream) 100%);
}

.bg-green {
  background: linear-gradient(180deg, var(--green-mist) 0%, var(--cream) 100%);
}

.bg-deep {
  background: linear-gradient(135deg, var(--blue-ink) 0%, #2B4A5E 100%);
  color: var(--cream);
}

.bg-deep h2,
.bg-deep h3 {
  color: #fff;
}

.bg-deep p {
  color: rgba(251, 252, 250, 0.78);
}

/* 弧形包裹区块 */
.arc-wrap {
  border-radius: var(--r-xl);
  padding: 56px;
  background: #fff;
  box-shadow: var(--shadow-arc);
  position: relative;
  overflow: hidden;
}

.arc-wrap.tight {
  padding: 40px;
}

/* ---------- 面包屑 ---------- */
.breadcrumb {
  padding: 22px 0;
  font-size: 13px;
  color: var(--muted);
  border-bottom: 1px solid var(--line);
  margin-bottom: 10px;
}

.breadcrumb a {
  color: var(--muted);
}

.breadcrumb a:hover {
  color: var(--blue-deep);
}

.breadcrumb span {
  margin: 0 8px;
  color: var(--blue);
}

.breadcrumb .current {
  color: var(--blue-ink);
  font-weight: 600;
}

/* ---------- 页面通用头部（非首页） ---------- */
.page-hero {
  padding: calc(var(--nav-h) + 60px) 0 60px;
  background: linear-gradient(135deg, var(--blue-mist) 0%, var(--green-mist) 100%);
  position: relative;
  overflow: hidden;
  border-radius: 0 0 var(--r-xl) var(--r-xl);
}

.page-hero::before {
  content: "";
  position: absolute;
  right: -80px;
  top: -80px;
  width: 300px;
  height: 300px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(143, 193, 219, 0.3) 0%, transparent 70%);
}

.page-hero::after {
  content: "";
  position: absolute;
  left: -60px;
  bottom: -60px;
  width: 240px;
  height: 240px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(168, 216, 185, 0.25) 0%, transparent 70%);
}

.page-hero .container {
  position: relative;
  z-index: 2;
}

.page-hero .eyebrow {
  display: inline-block;
  font-size: 12px;
  letter-spacing: 4px;
  color: var(--green-deep);
  text-transform: uppercase;
  font-family: var(--font-en);
  margin-bottom: 14px;
}

.page-hero h1 {
  font-size: 44px;
  color: var(--ink);
  letter-spacing: 1px;
  margin-bottom: 14px;
}

.page-hero p {
  color: var(--blue-ink);
  font-size: 16px;
  max-width: 640px;
}

/* ==========================================================================
   滚动渐入动画
   ========================================================================== */
.reveal {
  opacity: 0;
  transform: translateY(36px);
  transition: opacity 0.8s ease, transform 0.8s ease;
}

.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; }

/* ==========================================================================
   页脚
   ========================================================================== */
.site-foot {
  background: linear-gradient(160deg, var(--blue-ink) 0%, #23404F 100%);
  color: rgba(251, 252, 250, 0.72);
  padding: 64px 0 0;
  border-radius: var(--r-xl) var(--r-xl) 0 0;
  margin-top: 40px;
}

.foot-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1.2fr;
  gap: 40px;
  padding-bottom: 48px;
}

.foot-col h4 {
  color: #fff;
  font-size: 16px;
  margin-bottom: 18px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--blue-deep);
  display: inline-block;
}

.foot-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.foot-brand img {
  width: 40px;
  height: 40px;
}

.foot-brand strong {
  color: #fff;
  font-size: 19px;
}

.foot-col p {
  font-size: 13.5px;
  line-height: 1.8;
  color: rgba(251, 252, 250, 0.6);
}

.foot-col ul li {
  margin-bottom: 10px;
}

.foot-col ul li a {
  color: rgba(251, 252, 250, 0.65);
  font-size: 13.5px;
  transition: all 0.25s ease;
}

.foot-col ul li a:hover {
  color: var(--blue);
  padding-left: 4px;
}

.foot-contact li {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  margin-bottom: 12px;
  font-size: 13.5px;
  color: rgba(251, 252, 250, 0.65);
}

.foot-contact li svg {
  flex-shrink: 0;
  margin-top: 3px;
}

.foot-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding: 22px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.foot-bottom p {
  font-size: 13px;
  color: rgba(251, 252, 250, 0.5);
}

.foot-bottom a {
  color: rgba(251, 252, 250, 0.5);
}

.foot-bottom a:hover {
  color: var(--blue);
}

.foot-links {
  display: flex;
  gap: 20px;
}

.foot-links a {
  font-size: 13px;
  color: rgba(251, 252, 250, 0.5);
}

/* ==========================================================================
   响应式
   ========================================================================== */
@media (max-width: 1100px) {
  .nav-menu {
    gap: 0;
  }
  .nav-menu > .nav-item > a {
    padding: 10px 12px;
    font-size: 14px;
  }
}

@media (max-width: 900px) {
  :root {
    --nav-h: 60px;
  }

  .nav-inner {
    padding: 0 20px;
  }

  .nav-menu {
    position: fixed;
    top: var(--nav-h);
    right: -100%;
    width: 320px;
    max-width: 85vw;
    height: calc(100vh - var(--nav-h));
    background: #fff;
    flex-direction: column;
    align-items: stretch;
    padding: 24px;
    gap: 4px;
    overflow-y: auto;
    transition: right 0.35s ease;
    box-shadow: var(--shadow-lg);
  }

  .nav-menu.show {
    right: 0;
  }

  .nav-menu > .nav-item > a {
    padding: 13px 16px;
    border-radius: var(--r-sm);
    font-size: 15px;
  }

  .nav-dropdown {
    position: static;
    transform: none;
    opacity: 1;
    visibility: visible;
    box-shadow: none;
    border: none;
    padding: 0 0 0 16px;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease;
  }

  .nav-item.expanded .nav-dropdown {
    max-height: 500px;
  }

  .hamburger {
    display: flex;
  }

  .nav-cta {
    display: none;
  }

  .container {
    padding: 0 24px;
  }

  .section {
    padding: 60px 0;
  }

  .sec-head h2 {
    font-size: 30px;
  }

  .page-hero h1 {
    font-size: 34px;
  }

  .page-hero {
    padding: calc(var(--nav-h) + 40px) 0 40px;
    border-radius: 0 0 var(--r-lg) var(--r-lg);
  }

  .arc-wrap {
    padding: 32px;
    border-radius: var(--r-lg);
  }

  .arc-wrap.tight {
    padding: 24px;
  }

  .foot-grid {
    grid-template-columns: 1fr;
    gap: 28px;
  }

  .foot-bottom {
    flex-direction: column;
    text-align: center;
  }
}