* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Segoe UI", Roboto, Arial, sans-serif;
}
:root {
  --primary: #2563eb;
  --accent: #f97316;
  --dark: #1e293b;
  --gray: #64748b;
  --light-gray: #f1f5f9;
  --white: #ffffff;
  --radius: 999px;
}

/* =========核心：让页脚自动贴底========= */
html, body {
  height: 100%;
}
body {
  display: flex;
  flex-direction: column;
  color: var(--dark);
  background-color: var(--white);
  line-height: 1.6;
}
a {
  text-decoration: none;
  color: inherit;
}

/* 导航栏 固定顶部 */
.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 4rem;
  background: var(--white);
  box-shadow: 0 2px 10px rgba(0,0,0,0.06);
  position: sticky;
  top: 0;
  z-index: 999;
}
.logo {
  font-size: 26px;
  font-weight: 700;
  color: var(--primary);
}
.navbar nav {
  display: flex;
  gap: 1.8rem;
  align-items: center;
}
.navbar nav a.nav-link {
  font-size: 24px;
  color: var(--dark);
  padding: 10px 22px;
  border-radius: var(--radius);
  transition: all 0.2s;
}
.navbar nav a.nav-link:hover:not(.nav-active) {
  background-color: var(--light-gray);
}
.navbar nav a.nav-link.nav-active {
  background-color: var(--primary);
  color: #fff !important;
}
.navbar nav a.nav-link.nav-active:hover {
  background-color: #1d4ed8;
}

/* 主体内容自动填充剩余空间，把页脚往下推 */
.page-container {
  flex: 1;
}

/* 页面切换显隐 */
.page-content {
  display: none;
}
.page-content.active {
  display: block;
}

/* 首屏区域 */
.hero {
  text-align: center;
  padding: 6rem 2rem;
  background: linear-gradient(135deg, #f0f7ff 0%, #f8faff 100%);
}
.hero h1 {
  font-size: 42px;
  max-width: 800px;
  margin: 0 auto 16px;
  color: var(--dark);
}
.hero p {
  font-size: 18px;
  color: var(--gray);
  max-width: 650px;
  margin: 0 auto 32px;
}
.big-btn {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  padding: 16px 36px;
  border-radius: var(--radius);
  font-size: 18px;
  font-weight: 500;
  transition: background 0.2s;
}
.big-btn:hover {
  background: #ea580c;
}

/* 容器通用 */
.container {
  max-width: 1240px;
  margin: 0 auto;
  padding: 60px 20px;
}

/* 产品卡片 */
.product-grid {
  display: grid;
  /* 修改最小宽度，卡片基础宽度加大，适合长条布局 */
  grid-template-columns: repeat(auto-fill, minmax(400px, 1fr));
  gap: 28px;
  margin-top: 36px;
}
.card {
  background: #fff;
  border-radius: 16px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.06);
  /* 锁定长条比例：宽度 : 高度 = 3.4 : 1，数值越大越长 */
  aspect-ratio: 3.4 / 1;
  /* 删除 overflow:hidden ! 之前图片被裁切就是因为这个 */
  transition: transform 0.2s ease;
}
.card:hover {
  transform: translateY(-6px);
}
.card-body {
  padding: 24px;
}
.card h3 {
  font-size: 18px;
  margin-bottom: 8px;
}
.card p {
  color: var(--gray);
  font-size: 15px;
}

/* =========页脚样式（和截图深蓝色效果匹配）========= */
footer {
  text-align: center;
  padding: 40px 20px;
  background: #1e293b; /* 深蓝底色 */
  color: #cbd5e1;
}