一个最简单的页面：
<!DOCTYPE html>
<html>
<head>
<title>优化scroll</title>
<meta charset="utf-8">
<style type="text/css">
body{
width:2000px;
height: 2000px;
margin:0;
padding:0;
}
</style>
</head>
<body>
</body>
</html>
显示效果再熟悉不过了：
有点丑陋，可以通过css的方式，最快解决这个问题。（是的，不支持IE，及与其内核相关的浏览器）
处理代码如下，注释有说明：
<!DOCTYPE html>
<html>
<head>
<title>优化scroll</title>
<meta charset="utf-8">
<style type="text/css">
body{
width:2000px;
height: 2000px;
margin:0;
padding:0;
}
/*
width可以改变右边滚动条的宽度
height可以改变下边滚动条的高度
*/
::-webkit-scrollbar {
width: 9px;
height: 9px;
box-sizing: border-box;
}
/*
设置了滚动条按钮的样式图标，url我直接用了base64图片，无所谓啦
*/
::-webkit-scrollbar-button {
width: 9px;
height: 12px;
background: url(data:image/png;base64,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);
background-color: transparent;
background-repeat: no-repeat;
}
/*
corner角落的意思，可以改变Y滚动条与X滚动条交叉的右下角的样式
*/
::-webkit-scrollbar-corner {
background-color: #f1f1f1;
-webkit-border-radius: 1px;
}
/*
这就是滚动条的样式了
*/
::-webkit-scrollbar-thumb {
background-color: #E7E7E7;
border: 1px solid rgba(0,0,0,0.21);
-webkit-border-radius: 5px;
}
/*
悬浮时
*/
::-webkit-scrollbar-thumb:hover {
background-color: #F6F6F6;
border: 1px solid rgba(0,0,0,0.21);
}
/*
滚动条空白处的样式
*/
::-webkit-scrollbar-track-piece {
background-color: rgba(0,0,0,0.15);
-webkit-border-radius: 5px;
}
</style>
</head>
<body>
</body>
</html>
显示效果如下：
（好吧，我觉得是好看了那么一点点）