body {
    font-family: Arial, sans-serif;
}
.title {
    font-weight: bold;
    color: darkgreen;
}
.controls {
    margin-bottom: 20px;
}
.controls label, .controls input, .controls button, .controls select {
    margin-right: 10px;
}
.node circle {
    fill: #3498db;
    stroke: #000;
    stroke-width: 2px;
}
.node text {
    font: 12px sans-serif;
    text-anchor: middle;
    fill: #fff;
}
.link {
    fill: none;
    stroke: #ccc;
    stroke-width: 2px;
}
.highlight {
    fill: #e74c3c;
}
svg {
    border: 1px solid #ccc;
    background-color: #f9f9f9;
}