body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f9;
    color: #333;
    text-align: center;
}

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

header h1 {
    margin: 0;
}

nav ul {
    list-style: none;
    padding: 0;
}

nav ul li {
    display: inline;
    margin: 0 15px;
}

nav ul li a {
    color: white;
    text-decoration: none;
}

nav ul li a:hover {
    text-decoration: underline;
}

main {
    padding: 2em;
}

footer {
    background-color: #333;
    color: white;
    padding: 1em 0;
    position: fixed;
    width: 100%;
    bottom: 0;
}

section {
    margin-bottom: 2em;
}

.intro, .about, .contact {
    padding: 1em;
    background-color: #fff;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

.main-image, .about-image, .contact-image {
    width: 100%;
    max-width: 600px;
    height: auto;
    border-radius: 8px;
    margin-bottom: 1em;
}

/* 去掉列表项前的小圆点 */
ul {
    list-style-type: none;
    padding: 0;
}

ul li {
    margin: 0.5em 0;
}