:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --text-color: #333;
    --background-color: #f9f9f9;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
}

header {
    background-color: var(--primary-color);
    color: white;
    padding: 2rem;
    text-align: center;
}

nav {
    margin-top: 1rem;
    background-color: rgba(255, 255, 255, 0.1);
    padding: 1rem;
    border-radius: 5px;
}

nav ul {
    display: flex;
    justify-content: center;
    gap: 2rem;
    list-style: none;
}

nav a {
    color: white;
    text-decoration: none;
    padding: 0.5rem 1rem;
    transition: all 0.3s ease;
}

nav a:hover {
    background-color: var(--secondary-color);
    border-radius: 3px;
}

main {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1rem;
}

section {
    background-color: white;
    padding: 2rem;
    margin-bottom: 2rem;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

h2 {
    color: var(--primary-color);
    border-bottom: 2px solid var(--secondary-color);
    padding-bottom: 0.5rem;
    margin-bottom: 1.5rem;
}

ul {
    padding-left: 2rem;
}

li {
    margin-bottom: 0.8rem;
}

footer {
    text-align: center;
    padding: 1.5rem;
    background-color: var(--primary-color);
    color: white;
    margin-top: 3rem;
}

@media (max-width: 768px) {
    nav ul {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    section {
        padding: 1.5rem;
    }
}