.rfc-introduction-page {
    display: flex;
    gap: 2rem;
    max-width: 1400px;
    margin: 0 auto;
}

.main-section {
    flex: 2;
    min-width: 0;
}

.side-navigation {
    flex: 0 0 350px;
    position: sticky;
    top: 2rem;
    height: fit-content;
}

.page-header {
    text-align: center;
    margin-bottom: 3rem;
    padding: 2rem 0;
    border-bottom: 1px solid var(--border-color);
}

.page-title {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--primary-color), #7c3aed);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.page-subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
}

.content-section {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.intro-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--shadow);
}

.section-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-color);
}

.section-text {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.8;
}

.importance-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-top: 1rem;
}

.importance-item {
    text-align: center;
    padding: 1.5rem;
    background: var(--sidebar-bg);
    border-radius: 0.75rem;
    transition: var(--transition);
}

.importance-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.importance-icon {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.importance-item h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.importance-item p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.status-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-top: 1rem;
}

.status-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    background: var(--sidebar-bg);
    border-radius: 0.5rem;
}

.status-badge {
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    min-width: 120px;
    text-align: center;
}

.status-badge.standard { background: #dcfce7; color: #166534; }
.status-badge.proposed { background: #dbeafe; color: #1e40af; }
.status-badge.draft { background: #fef3c7; color: #92400e; }
.status-badge.informational { background: #e0e7ff; color: #5b21b6; }
.status-badge.experimental { background: #fed7d7; color: #c53030; }
.status-badge.historic { background: #f3f4f6; color: #4b5563; }

.status-desc {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.nav-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 1rem;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.nav-title {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--text-color);
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.nav-menu {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.rfc-nav-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    border-radius: 0.75rem;
    text-decoration: none;
    color: var(--text-color);
    transition: var(--transition);
    border: 1px solid transparent;
}

.rfc-nav-item:hover {
    background: rgba(37, 99, 235, 0.05);
    border-color: var(--primary-color);
    transform: translateX(4px);
}

.nav-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.nav-content {
    flex: 1;
    min-width: 0;
}

.nav-name {
    display: block;
    font-weight: 600;
    font-size: 0.95rem;
    margin-bottom: 0.25rem;
}

.nav-desc {
    display: block;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.rfc-nav-arrow {
    font-size: 1.2rem;
    color: var(--text-secondary);
    transition: var(--transition);
}

.rfc-nav-item:hover .rfc-nav-arrow {
    color: var(--primary-color);
    transform: translateX(4px);
}

.stats-card {
    background: linear-gradient(135deg, var(--primary-color), #7c3aed);
    color: white;
    border: none;
}

.stats-card .nav-title {
    color: white;
    border-color: rgba(255, 255, 255, 0.2);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
}

.stat-item {
    text-align: center;
}

.stat-number {
    font-size: 1.5rem;
    font-weight: 800;
    margin-bottom: 0.25rem;
}

.stat-label {
    font-size: 0.8rem;
    opacity: 0.9;
}

/* 响应式设计 */
@media (max-width: 1024px) {
    .rfc-introduction-page {
        flex-direction: column;
    }

    .side-navigation {
        position: static;
        flex: none;
    }

    .stats-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 768px) {
    .page-title {
        font-size: 2rem;
    }

    .importance-grid {
        grid-template-columns: 1fr;
    }

    .rfc-nav-item {
        padding: 0.75rem;
    }

    .nav-name {
        font-size: 0.9rem;
    }

    .nav-desc {
        font-size: 0.75rem;
    }
}