/* 重置样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f5f7fa;
}

/* 容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 头部 */
.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 1rem 0;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.8rem;
    font-weight: 700;
}

.nav ul {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: opacity 0.3s ease;
}

.nav a:hover {
    opacity: 0.8;
}

/* 主内容 */
.main {
    padding: 2rem 0;
}

.content {
    background: white;
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}

.content h2 {
    color: #2d3748;
    margin-bottom: 1rem;
    font-size: 2rem;
}

.content p {
    color: #4a5568;
    margin-bottom: 2rem;
    font-size: 1.1rem;
}

/* 图表占位符 */
.chart-placeholder {
    background: #f7fafc;
    border: 2px dashed #cbd5e0;
    border-radius: 8px;
    padding: 3rem;
    text-align: center;
    color: #718096;
    margin-top: 2rem;
    transition: all 0.3s ease;
}

.chart-placeholder:hover {
    border-color: #667eea;
    background: #edf2f7;
}

/* 页脚 */
.footer {
    background: #2d3748;
    color: white;
    padding: 1.5rem 0;
    margin-top: 2rem;
    text-align: center;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .header .container {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav ul {
        gap: 1rem;
    }
    
    .content {
        padding: 1.5rem;
    }
    
    .content h2 {
        font-size: 1.6rem;
    }
}