/* 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f4f4f4;
}

/* 头部样式 */
header {
    background-color: #333;
    color: #fff;
    padding: 1rem;
    text-align: center;
}

nav ul {
    list-style: none;
    margin-top: 1rem;
}

nav ul li {
    display: inline;
    margin: 0 10px;
}

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

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

/* 主内容样式 */
main {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 2rem;
}

section {
    background-color: #fff;
    padding: 2rem;
    margin-bottom: 2rem;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

h2 {
    color: #333;
    margin-bottom: 1rem;
}

.sample-image {
    max-width: 100%;
    height: auto;
    margin: 1rem 0;
    border-radius: 5px;
}

/* 按钮样式 */
#demo-button {
    background-color: #333;
    color: #fff;
    border: none;
    padding: 10px 20px;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
}

#demo-button:hover {
    background-color: #555;
}

#demo-text {
    margin-top: 1rem;
    font-weight: bold;
}

/* 页脚样式 */
footer {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 1rem;
    margin-top: 2rem;
}

/* 响应式设计 */
@media (max-width: 768px) {
    main {
        padding: 0 1rem;
    }
    
    section {
        padding: 1rem;
    }
    
    nav ul li {
        display: block;
        margin: 5px 0;
    }
}