:root {
    --primary: #1e4b69;
    --accent: rgb(70, 180, 200);
    --bg: #f5f7fa;
    --entity-org: #8e44ad;
    --entity-user: #2980b9;
    --entity-project: #27ae60;
    --entity-task: #e67e22;
}

* {
    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: 960px;
    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;
}

.er-area {
    background: white;
    border-radius: 12px;
    padding: 30px 20px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    position: relative;
    margin-bottom: 20px;
    min-height: 200px;
}

.er-svg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1;
}

.entities-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    position: relative;
    z-index: 2;
}

.entity-card {
    border-radius: 10px;
    overflow: hidden;
    border: 2px solid #e0e0e0;
    background: white;
    cursor: pointer;
    transition: all 0.25s;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.06);
}

.entity-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.12);
}

.entity-card.active {
    box-shadow: 0 4px 16px rgba(70, 180, 200, 0.3);
    border-color: var(--accent);
}

.entity-header {
    padding: 12px 14px;
    color: white;
    font-weight: 700;
    font-size: 0.95rem;
    text-align: center;
}

.entity-header.org { background: var(--entity-org); }
.entity-header.user { background: var(--entity-user); }
.entity-header.project { background: var(--entity-project); }
.entity-header.task { background: var(--entity-task); }

.entity-attrs {
    padding: 8px 12px;
}

.entity-attr {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 4px 0;
    font-size: 0.8rem;
    color: #555;
}

.attr-key {
    font-size: 0.65rem;
    font-weight: 700;
    padding: 1px 5px;
    border-radius: 3px;
    color: white;
    flex-shrink: 0;
}

.attr-key.pk { background: #2980b9; }
.attr-key.fk { background: #27ae60; }

.relationship-line {
    cursor: pointer;
    pointer-events: stroke;
}

.relationship-label {
    font-size: 12px;
    fill: #777;
    font-weight: 600;
    pointer-events: all;
    cursor: pointer;
}

.detail-panel {
    background: white;
    border-radius: 12px;
    padding: 20px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    min-height: 80px;
}

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

.detail-content {
    display: none;
}

.detail-content.visible {
    display: block;
}

.detail-title {
    color: var(--primary);
    font-size: 1.1rem;
    margin-bottom: 12px;
}

.detail-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.85rem;
}

.detail-table th {
    background: var(--primary);
    color: white;
    padding: 8px 12px;
    text-align: left;
}

.detail-table td {
    padding: 7px 12px;
    border-bottom: 1px solid #eee;
}

.detail-table tr:nth-child(even) {
    background: #f8f9fa;
}

.tooltip {
    position: fixed;
    background: var(--primary);
    color: white;
    padding: 10px 14px;
    border-radius: 8px;
    font-size: 0.85rem;
    max-width: 280px;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.2s;
    z-index: 100;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
    line-height: 1.4;
}

.tooltip.visible {
    opacity: 1;
}

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

    .er-svg {
        display: none;
    }
}