/* 让页面居中、简单干净 */
body {
    font-family: Arial, sans-serif;
    background: #f5f5f5;
    text-align: center;
    padding-top: 80px;
}

.box {
    background: white;
    max-width: 400px;
    margin: 0 auto;
    padding: 40px;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}

.btn {
    display: inline-block;
    margin-top: 20px;
    padding: 10px 20px;
    background: #0099ff;
    color: white;
    text-decoration: none;
    border-radius: 5px;
}