* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: "Microsoft YaHei", Arial, sans-serif;
  color: #222;
  line-height: 1.6;
}

/* ===== Header ===== */
header {
  background: #0b3d91;
  color: #fff;
  padding: 14px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
}
header .logo {
  font-size: 20px;
  font-weight: bold;
  white-space: nowrap;
}

nav {
  display: flex;
  gap: 20px;
}
nav a {
  color: #fff;
  text-decoration: none;
  font-size: 15px;
  white-space: nowrap;
}
nav a:hover { text-decoration: underline; }

/* 当前页面高亮 */
nav a.active {
  text-decoration: underline;
  font-weight: bold;
}

/* 汉堡按钮 */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.menu-toggle span {
  display: block;
  width: 24px;
  height: 3px;
  background: #fff;
  margin: 5px 0;
  border-radius: 2px;
}

/* ===== Banner ===== */
.banner {
  background: linear-gradient(135deg, #0b3d91, #1976d2);
  color: #fff;
  padding: 60px 20px;
  text-align: center;
}
.banner h1 { font-size: 32px; margin-bottom: 12px; }
.banner p { font-size: 17px; opacity: .9; }

/* ===== 内容区 ===== */
section {
  max-width: 1100px;
  margin: 0 auto;
  padding: 40px 20px;
}
.products {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
  margin-top: 20px;
}
.card {
  border: 1px solid #e5e5e5;
  border-radius: 8px;
  padding: 18px;
  background: #fafafa;
}
.card h3 { color: #0b3d91; margin-bottom: 8px; }
.about p { margin-top: 10px; }

/* ===== Footer ===== */
footer {
  background: rgba(0,0,0,0.08);
  color: #0b3d91;
  text-align: center;
  padding: 22px;
  font-size: 14px;
}
footer a {
  color: #0b3d91;
  text-decoration: none;
}
footer a:hover { text-decoration: underline; }

/* ===== 手机端适配 ===== */
@media (max-width: 768px) {
  .menu-toggle { display: block; }

  nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: #0b3d91;
    flex-direction: column;
    padding: 10px 20px;
    box-shadow: 0 4px 10px rgba(0,0,0,.2);
  }
  nav a {
    padding: 10px 0;
    border-bottom: 1px solid rgba(255,255,255,.1);
  }
  nav a:last-child { border-bottom: none; }

  nav.open { display: flex; }
}

/* ===== 手机端适配 ===== */
@media (max-width: 768px) {
  .menu-toggle { display: block; }

  nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: #0b3d91;
    flex-direction: column;
    padding: 10px 20px;
    box-shadow: 0 4px 10px rgba(0,0,0,.2);
    z-index: 1000;
  }
  nav a {
    padding: 10px 0;
    border-bottom: 1px solid rgba(255,255,255,.1);
  }
  nav a:last-child { border-bottom: none; }

  nav.open { display: flex; }

  /* 遮罩层 */
  .nav-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0,0,0,0.4);
    z-index: 999;
  }
  .nav-overlay.show { display: block; }
}