:root {
    --primary: #1e4b69;
    --accent: rgb(70, 180, 200);
    --bg: #f5f7fa;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', system-ui, sans-serif;
    background: var(--bg);
    color: #333;
    padding: 20px;
    display: flex;
    justify-content: center;
}

.container {
    max-width: 1000px;
    width: 100%;
}

h1 {
    color: var(--primary);
    text-align: center;
    font-size: 1.6rem;
    margin-bottom: 4px;
}

.subtitle {
    text-align: center;
    color: #666;
    margin-bottom: 24px;
    font-size: 0.95rem;
}

.tree-area {
    background: white;
    border-radius: 12px;
    padding: 30px 20px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    margin-bottom: 20px;
}

.tree-root {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.question-node {
    background: var(--primary);
    color: white;
    padding: 14px 24px;
    border-radius: 12px;
    font-weight: 700;
    font-size: 1.1rem;
    text-align: center;
    margin-bottom: 20px;
    box-shadow: 0 3px 10px rgba(30, 75, 105, 0.25);
}

.branches {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    width: 100%;
}

.branch {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.branch-connector {
    width: 2px;
    height: 20px;
    background: #ccc;
}

.condition-label {
    background: #e8f4f8;
    color: var(--primary);
    padding: 8px 14px;
    border-radius: 8px;
    font-size: 0.82rem;
    font-weight: 600;
    text-align: center;
    border: 1px solid #d0e8ef;
}

.arrow-down {
    width: 0;
    height: 0;
    border-left: 8px solid transparent;
    border-right: 8px solid transparent;
    border-top: 10px solid #ccc;
}

.db-node {
    padding: 14px 16px;
    border-radius: 10px;
    text-align: center;
    cursor: pointer;
    transition: all 0.25s;
    border: 2px solid #e0e0e0;
    background: white;
    width: 100%;
}

.db-node:hover {
    transform: translateY(-3px);
    box-shadow: 0 4px 14px rgba(0, 0, 0, 0.12);
    border-color: var(--accent);
}

.db-node.active {
    border-color: var(--accent);
    background: #f0fbfd;
    box-shadow: 0 4px 14px rgba(70, 180, 200, 0.3);
}

.db-icon {
    font-size: 1.8rem;
    margin-bottom: 6px;
}

.db-name {
    font-weight: 700;
    color: var(--primary);
    font-size: 0.95rem;
    margin-bottom: 2px;
}

.db-example {
    font-size: 0.78rem;
    color: #888;
}

.detail-panel {
    background: white;
    border-radius: 12px;
    padding: 24px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    min-height: 120px;
    transition: all 0.3s;
}

.detail-placeholder {
    color: #aaa;
    text-align: center;
    font-style: italic;
}

.detail-title {
    color: var(--primary);
    font-size: 1.2rem;
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.detail-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

.detail-section h4 {
    color: var(--primary);
    margin-bottom: 6px;
    font-size: 0.95rem;
}

.detail-section ul {
    list-style: none;
    padding: 0;
}

.detail-section li {
    padding: 4px 0;
    font-size: 0.88rem;
    color: #555;
    position: relative;
    padding-left: 16px;
}

.detail-section li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 10px;
    width: 6px;
    height: 6px;
    border-radius: 50%;
}

.use-cases li::before {
    background: #27ae60;
}

.tradeoffs li::before {
    background: #e67e22;
}

@media (max-width: 700px) {
    .branches {
        grid-template-columns: 1fr 1fr;
    }

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

@media (max-width: 480px) {
    .branches {
        grid-template-columns: 1fr;
    }
}