我想在div中添加图例，以便在散点图数量增加时自动滚动。以下是我的示例代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<script type="text/javascript" src="http://mbostock.github.com/d3/d3.js"></script>
<style type="text/css">
.axis path,
.axis line {
fill: none;
stroke: black;
shape-rendering: crispEdges;
}
.axis text {
font-family: sans-serif;
font-size: 11px;
}
.y1 {
fill: white;
stroke: orange;
stroke-width: 1.5px;
}
.y2 {
fill: white;
stroke: red;
stroke-width: 1.5px;
}
.y3 {
fill: white;
stroke: steelblue;
stroke-width: 1.5px;
}
.line {
fill: none;
stroke-width: 1.5px;
}
div.tooltip {
position: absolute;
text-align: center;
width: 50px;
height: 10px;
padding: 5px;
font: …