:root {
    --primary: #2c3e50;
    --secondary: #3498db;
    --accent: #e74c3c;
    --light-bg: #f8f9fa;
    --dark-text: #2c3e50;
    --medium-text: #555;
    --border: #eaecef;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.container_longtougu {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    background: #fff;
    box-shadow: var(--shadow);
    overflow: hidden;
}

.header_longtougu {
    background: linear-gradient(135deg, #0f0c29, #302b63);;
    color: white;
    padding: 28px 30px;
    text-align: center;
}


.knowledge-tree {
    padding: 25px;
}

/* 折叠面板样式 */
.accordion {
    margin-bottom: 15px;
    border: 1px solid var(--border);
    border-radius: 10px;
    overflow: hidden;
    background: #fff;
}

.accordion-header {
    background: var(--light-bg);
    padding: 18px 22px;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 600;
    font-size: 18px;
    color: var(--dark-text);
    transition: background 0.2s;
}

.accordion-header:hover {
    background: #f0f2f5;
}

.accordion-header::after {
    content: "›";
    font-size: 22px;
    transition: transform 0.3s;
    color: #7f8c8d;
}

.accordion.active .accordion-header::after {
    transform: rotate(90deg);
}

.accordion-content {
    padding: 0;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease;
    background: #fff;
}

.accordion.active .accordion-content {
    padding: 20px 22px;
    max-height: 3000px;
}

.content-item {
    margin-bottom: 18px;
    padding-bottom: 18px;
    border-bottom: 1px dashed var(--border);
}

.content-item:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.content-item h3 {
    font-size: 17px;
    color: var(--dark-text);
    margin-bottom: 10px;
    font-weight: 600;
}

.content-item p {
    font-size: 14px;
    color: var(--medium-text);
    margin-bottom: 8px;
    line-height: 1.7;
}

.content-item ul {
    list-style: none;
    font-size: 14px;
    color: var(--medium-text);
}

.content-item ul li {
    margin-bottom: 8px;
    padding-left: 20px;
    position: relative;
    line-height: 1.6;
}

.content-item ul li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--secondary);
    font-weight: bold;
}

.highlight {
    color: var(--accent);
    font-weight: 600;
}

.strategy-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
    margin-top: 15px;
}

.strategy-card {
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px;
    background: #fafbfc;
}

.strategy-card h4 {
    font-size: 15px;
    color: var(--dark-text);
    margin-bottom: 10px;
    font-weight: 600;
}

/* 响应式调整 */
@media (max-width: 768px) {
    .header h1 {
        font-size: 22px;
    }

    .accordion-header {
        font-size: 16px;
        padding: 14px 18px;
    }

    .content-item h3 {
        font-size: 16px;
    }

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