body {
    display: flex;
    justify-content: center; /* 水平居中 */
    align-items: center; /* 垂直居中 */
    background-color: #f4f4f4;
}

.content {
    max-width: 70%; /* 根据需要调整宽度 */
    width: 70%;
    background-color: white;
    padding: 20px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
    text-align: left; /* 确保内部文本左对齐 */
}
header {
    background-color: #333;
    color: white;
    padding: 1em 0;
    text-align: center;
}

main {
    padding: 20px;
}

section {
    background-color: white;
    margin-bottom: 20px;
    padding: 15px;
    border-radius: 5px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}

footer {
    text-align: center;
    padding: 10px 0;
    background-color: #333;
    color: white;
    position: fixed;
    width: 70%;
    bottom: 0;
}