/* ==========================================================================
   首页延伸卡片（Extension Card）
   ========================================================================== */
.extension-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1.25rem 1.5rem 1rem;
    margin-top: 2rem;
    box-shadow: var(--shadow-sm);
    display: flex;
    gap: 1.25rem;
    align-items: stretch;
}
.extension-accent {
    width: 4px;
    border-radius: 4px;
    background: linear-gradient(180deg, var(--primary-color), var(--secondary-color));
    flex-shrink: 0;
}
.extension-content {
    flex: 1;
    text-align: left;
}
.extension-label {
    font-size: 0.7rem;
    letter-spacing: 0.15em;
    color: var(--text-muted);
    text-transform: uppercase;
    margin-bottom: 0.3rem;
}
.extension-desc {
    font-size: 1rem;
    line-height: 1.7;
    color: var(--text-primary);
    max-width: 600px;
    margin: 0 0 0.2rem 0;
}
.extension-link-wrap {
    font-size: 0.95rem;
    line-height: 1.7;
    color: var(--text-secondary);
    margin: 0;
}
.extension-link {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    border-bottom: 1px solid transparent;
    transition: border-color 0.2s ease;
}
.extension-link:hover {
    border-bottom-color: var(--primary-color);
}