/* ============================================================
   康瑞得 KRD HEALTH 官网 - 公共样式
   包含：CSS 变量、重置、导航、页脚、按钮、通用栅格、响应式
   ============================================================ */

/* ---------- 1. CSS 变量（主色调：医疗蓝） ---------- */
:root {
  --color-primary: #1565C0;      /* 医疗蓝主色 */
  --color-primary-dark: #0D47A1; /* 深蓝（悬停/标题强调） */
  --color-primary-light: #E3F2FD;/* 浅蓝背景 */
  --color-text: #1F2937;         /* 正文深灰 */
  --color-text-light: #6B7280;   /* 次要文字 */
  --color-bg: #FFFFFF;           /* 页面背景 */
  --color-bg-gray: #F5F7FA;      /* 浅灰区块背景 */
  --color-border: #E5E7EB;       /* 边框 */
  --shadow-card: 0 2px 12px rgba(21, 101, 192, 0.08); /* 卡片阴影 */
  --radius: 8px;                 /* 统一圆角 */
  --header-h: 72px;              /* 顶部导航高度 */
}

/* ---------- 2. 基础重置 ---------- */
* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  font-size: 16px;
  /* 预留顶部固定导航的高度 */
  padding-top: var(--header-h);
}

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

a { text-decoration: none; color: inherit; transition: color .2s; }

ul, ol { list-style: none; }

.container {
  width: 90%;
  max-width: 1200px;
  margin: 0 auto;
}

/* ---------- 3. 顶部导航 ---------- */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--header-h);
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

/* Logo 区域 */
.logo { display: flex; align-items: center; gap: 10px; }
.logo img { height: 48px; width: auto; }
.logo .logo-name {
  font-size: 22px;
  font-weight: 700;
  color: var(--color-primary-dark);
  letter-spacing: 2px;
}
.logo .logo-en {
  display: block;
  font-size: 11px;
  font-weight: 400;
  color: var(--color-text-light);
  letter-spacing: 4px;
}

/* 导航菜单 */
.main-nav ul { display: flex; gap: 8px; }
.main-nav a {
  display: block;
  padding: 8px 18px;
  font-size: 16px;
  color: var(--color-text);
  border-radius: var(--radius);
  position: relative;
}
.main-nav a:hover { color: var(--color-primary); }
/* 当前页高亮：文字变主色 + 底部短横线 */
.main-nav a.active {
  color: var(--color-primary);
  font-weight: 600;
}
.main-nav a.active::after {
  content: "";
  position: absolute;
  left: 50%; bottom: 0;
  transform: translateX(-50%);
  width: 24px; height: 3px;
  border-radius: 2px;
  background: var(--color-primary);
}

/* 移动端汉堡按钮（桌面端隐藏） */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px; height: 40px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}
.nav-toggle span {
  display: block;
  height: 2px;
  background: var(--color-primary-dark);
  border-radius: 2px;
  transition: transform .3s, opacity .3s;
}
/* 汉堡变叉号 */
.nav-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- 4. 页面 Banner（内页顶部标题区） ---------- */
.page-banner {
  padding: 60px 0;
  text-align: center;
  color: #fff;
  background: linear-gradient(135deg, #0D47A1 0%, #1976D2 60%, #42A5F5 100%);
}
.page-banner h1 { font-size: 34px; letter-spacing: 4px; }
.page-banner p { margin-top: 8px; opacity: .85; font-size: 15px; letter-spacing: 1px; }

/* ---------- 5. 通用区块与标题 ---------- */
.section { padding: 80px 0; }
.section.gray { background: var(--color-bg-gray); }

.section-title { text-align: center; margin-bottom: 50px; }
.section-title h2 {
  font-size: 30px;
  color: var(--color-primary-dark);
  letter-spacing: 2px;
}
.section-title .en {
  display: block;
  font-size: 13px;
  color: var(--color-text-light);
  letter-spacing: 3px;
  text-transform: uppercase;
  margin-top: 4px;
}
/* 标题下的装饰短线 */
.section-title::after {
  content: "";
  display: block;
  width: 48px; height: 3px;
  margin: 16px auto 0;
  border-radius: 2px;
  background: var(--color-primary);
}

/* ---------- 6. 按钮 ---------- */
.btn {
  display: inline-block;
  padding: 12px 34px;
  border-radius: var(--radius);
  font-size: 16px;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all .25s;
}
.btn-primary {
  background: var(--color-primary);
  color: #fff;
}
.btn-primary:hover {
  background: var(--color-primary-dark);
  box-shadow: 0 4px 14px rgba(21, 101, 192, .35);
}
.btn-outline {
  border-color: #fff;
  color: #fff;
}
.btn-outline:hover { background: rgba(255, 255, 255, .15); }

/* ---------- 7. 卡片网格（产品/新闻通用） ---------- */
.grid {
  display: grid;
  gap: 28px;
  grid-template-columns: repeat(3, 1fr); /* 桌面端三列 */
}
.grid-4 { grid-template-columns: repeat(4, 1fr); } /* 桌面端四列 */

/* 通用卡片 */
.card {
  background: #fff;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-card);
  transition: transform .25s, box-shadow .25s;
}
.card:hover {
  transform: translateY(-6px);
  box-shadow: 0 8px 24px rgba(21, 101, 192, .16);
}
.card .card-img {
  height: 200px;
  background: linear-gradient(135deg, #E3F2FD, #BBDEFB); /* 图片占位渐变 */
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-primary);
  font-size: 15px;
  letter-spacing: 1px;
}
.card .card-body { padding: 20px; }
.card .card-body h3 {
  font-size: 18px;
  color: var(--color-text);
  margin-bottom: 8px;
}
.card .card-body p {
  font-size: 14px;
  color: var(--color-text-light);
}

/* ---------- 8. 页脚 ---------- */
.site-footer {
  background: #0D2B52; /* 深海军蓝 */
  color: #B8C7DB;
  padding: 60px 0 0;
  margin-top: 0;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1.2fr;
  gap: 40px;
  padding-bottom: 40px;
}
.site-footer h4 {
  color: #fff;
  font-size: 17px;
  margin-bottom: 16px;
  letter-spacing: 1px;
}
.site-footer p, .site-footer li { font-size: 14px; line-height: 2; }
.site-footer a:hover { color: #fff; }

/* 页脚版权条 */
.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, .12);
  padding: 18px 0;
  text-align: center;
  font-size: 13px;
  color: #7E93AF;
  line-height: 1.9;
}

.footer-bottom a {
  color: #7E93AF;
  text-decoration: none;
  transition: color .2s;
}

.footer-bottom a:hover {
  color: #fff;
  text-decoration: underline;
}

/* ---------- 9. 返回顶部按钮 ---------- */
.back-top {
  position: fixed;
  right: 24px; bottom: 32px;
  width: 44px; height: 44px;
  border-radius: 50%;
  border: none;
  background: var(--color-primary);
  color: #fff;
  font-size: 20px;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: opacity .3s, visibility .3s;
  z-index: 999;
  box-shadow: 0 4px 12px rgba(21, 101, 192, .4);
}
.back-top.show { opacity: 1; visibility: visible; }
.back-top:hover { background: var(--color-primary-dark); }

/* ---------- 10. 滚动淡入动效 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity .6s ease, transform .6s ease;
}
.reveal.visible { opacity: 1; transform: none; }

/* ============================================================
   响应式适配
   ============================================================ */

/* 平板：<=1024px，四列降为两列 */
@media (max-width: 1024px) {
  .grid, .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}

/* 手机：<=768px */
@media (max-width: 768px) {
  :root { --header-h: 60px; }

  .logo .logo-name { font-size: 18px; }
  .logo img { height: 40px; }

  /* 汉堡按钮显示 */
  .nav-toggle { display: flex; }

  /* 导航收进抽屉菜单 */
  .main-nav {
    position: fixed;
    top: var(--header-h);
    left: 0; right: 0;
    background: #fff;
    border-bottom: 1px solid var(--color-border);
    box-shadow: 0 8px 16px rgba(0, 0, 0, .08);
    max-height: 0;
    overflow: hidden;
    transition: max-height .35s ease;
  }
  .main-nav.open { max-height: 400px; }
  .main-nav ul {
    flex-direction: column;
    gap: 0;
    padding: 8px 0;
  }
  .main-nav a { padding: 12px 6%; }
  .main-nav a.active::after { display: none; }
  .main-nav a.active { background: var(--color-primary-light); }

  /* 区块与标题缩小 */
  .section { padding: 50px 0; }
  .section-title h2 { font-size: 24px; }
  .page-banner { padding: 40px 0; }
  .page-banner h1 { font-size: 26px; }

  /* 网格全部降为单列 */
  .grid, .grid-4 { grid-template-columns: 1fr; }

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