/* 基础样式 */
:root {
    --primary-color: #4285f4;
    --secondary-color: #34a853;
    --accent-color: #ea4335;
    --light-gray: #f5f5f5;
    --dark-gray: #333;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--light-gray);
    color: var(--dark-gray);
    line-height: 1.6;
}

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

header {
    text-align: center;
    margin-bottom: 3rem;
}

header h1 {
    font-size: 2.5rem;
    color: var(--primary-color);
}

.chart-selection {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.chart-card {
    background: white;
    border-radius: 10px;
    padding: 2rem;
    text-decoration: none;
    color: inherit;
    display: block;
    transition: transform 0.3s, box-shadow 0.3s;
    box-shadow: var(--shadow);
}

.chart-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
}

.chart-icon {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
    height: 80px;
}

.chart-card h2 {
    font-size: 1.8rem;
    margin-bottom: 1rem;
    color: var(--dark-gray);
}

.chart-card ul {
    list-style-position: inside;
    padding-left: 0.5rem;
}

.chart-card li {
    margin-bottom: 0.5rem;
    color: #666;
}

footer {
    text-align: center;
    margin-top: 3rem;
    color: #666;
    font-size: 0.9rem;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .main-container {
        padding: 1rem;
    }

    header h1 {
        font-size: 2rem;
    }

    .chart-selection {
        grid-template-columns: 1fr;
    }
}