body {
  font-family: 'Arial', sans-serif;
  margin: 0;
  padding: 0;
  background: #fff;
  color: #333;
}
header.hero {
height: 300px;
  
  color: white;
  padding-top: 80px;
  text-align: center;
background-image: url('images/bg.jpg'); 
  background-size: cover;
  background-position: center center;
}
.logo {
  height: 90px;
  margin-bottom: 10px;
}
nav {
  position: fixed;
  top: 0;
  width: 100%;
  background-color: #268892;
  z-index: 999;
  padding: 15px 0;
  text-align: center;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1); /* 可选阴影增加立体感 */
}

nav a {
  margin: 0 20px;
  color: #fff;
  text-decoration: none;
  font-weight: bold;
}main {
  padding: 40px;
}

section img {
  max-width: 100%;
  height: 400px;
  display: block;
  margin: 0 auto;
  image-rendering: auto;           /* 默认 */
  image-rendering: crisp-edges;    /* 尝试更清晰 */
  image-rendering: -webkit-optimize-contrast;
}

footer {
  background: #268892;
  color: white;
  text-align: center;
  padding: 10px 0;
}