body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
}

header {
    background-color: #4CAF50;
    color: white;
    padding: 1em 0;
    text-align: center;
}

header h1 {
    margin: 0;
}

main {
    display: flex;
    flex-wrap: wrap; /* 允许内容换行 */
    justify-content: space-around;
    padding: 1em;
}

.section {
    text-align: center;
    width: 100%; /* 默认宽度为100% */
    margin: 1em 0; /* 只在上下添加外边距 */
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
    transition: transform 0.3s;
}

/* 为大屏幕设备设置宽度 */
@media (min-width: 768px) {
    .section {
        width: calc(33.333% - 2em); /* 三个栏目并排，考虑外边距 */
    }
}

.section:hover {
    transform: translateY(-10px);
}

.section a {
    text-decoration: none;
    color: black;
}

.responsive-img {
    width: 100%;
    height: auto;
    border-radius: 8px 8px 0 0;
}

footer {
    text-align: center;
    padding: 1em 0;
    background-color: #4CAF50;
    color: white;
}