jquery如何实现边栏滚动固定跟随？

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">

	<style>
		body{
			font-size:80px;
			margin:0;
			padding:0;
		}
		.fl{
			float:left;
			width: 70%;
			height: 2210px;
			background: pink;
		}
		.fr{
			float:right;
			width: 29%;
			height: 1000px;
			background: cyan;
		}
	</style>
</head>
<body>
	<div class="fl">左边
		<div style="color:red">1</div>
		<div style="color:orange">2</div>
		<div style="color:red">3</div>
		<div style="color:orange">4</div>
		<div style="color:red">5</div>
		<div style="color:blue">6</div>
		<div style="color:orange">7</div>
		<div style="color:red">8</div>
		<div style="color:orange">9</div>
		<div style="color:white">10</div>
		<div style="color:orange">11</div>
		<div style="color:red">12</div>
		<div style="color:green">13</div>
		<div sty...

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