body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}
header {
    background: #004a99; /* 专业光学蓝 */
    color: #fff;
    padding: 2rem;
    text-align: center;
}
h2 {
    color: #004a99;
}