/* 基础变量和重置 */
:root {
    --color-primary: #15214b;
    --color-accent: #9eff66;
    --color-text: #333;
    --color-light-bg: #f8f9fa;
    --color-border: #e9ecef;
    --container-width: 1200px;
    --header-height: 70px;
}

* {
    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: var(--color-text);
    background-color: var(--color-light-bg);
}

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 1rem;
}

/* Header 样式 */
.site-header {
    background-color: var(--color-primary);
    color: white;
    height: var(--header-height);
    display: flex;
    align-items: center;
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
}

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

.domain-extension {
    color: var(--color-accent);
}

/* Welcome Section 样式 */
.welcome-section {
    padding: 4rem 0;
    text-align: center;
    background-color: white;
    border-bottom: 1px solid var(--color-border);
}

.welcome-section h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: var(--color-primary);
}

.welcome-section p {
    font-size: 1.2rem;
    color: #666;
    max-width: 600px;
    margin: 0 auto;
}

/* Navigation Grid 样式 */
.main-content {
    padding: 4rem 0;
}

.tense-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    padding: 1rem 0;
}

.tense-card {
    background: white;
    border-radius: 8px;
    padding: 2rem;
    text-decoration: none;
    color: var(--color-text);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid var(--color-border);
}

.tense-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.15);
}

.tense-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--color-primary);
}

.tense-card p {
    color: #666;
}

/* Footer 样式 */
.site-footer {
    background-color: var(--color-primary);
    color: white;
    padding: 2rem 0;
    margin-top: auto;
}

.site-footer p {
    text-align: center;
    font-size: 0.9rem;
    opacity: 0.8;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .welcome-section {
        padding: 3rem 0;
    }

    .welcome-section h2 {
        font-size: 2rem;
    }

    .tense-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
        padding: 1rem;
    }

    .tense-card {
        padding: 1.5rem;
    }
}

@media (max-width: 480px) {
    .site-title {
        font-size: 1.5rem;
    }

    .welcome-section h2 {
        font-size: 1.8rem;
    }

    .welcome-section p {
        font-size: 1rem;
    }
}