没等高布局之前：
代码：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style>
.test{
300px;
margin:0 auto;color:#fff;
background:#ccc;
}
.left{
30%;float:left; background:green;
}
.right{
70%;float:left;background:red;
}
</style>
</head>
<body>
<div class="test">
<div class="left">左</div>
<div class="right">右<br>fdfd <br>hang <br>oooo</div>
</div>
</body>
</html>
效果图：
登高布局之后：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style>
.test{
300px;
margin:0 auto;color:#fff;
background:#ccc;
overflow:hidden;
}
.left{
30%;float:left; background:green;
padding-bottom:1000px;
margin-bottom:-1000px;
}
.right{
70%;float:left;background:red;
padding-bottom:1000px;
margin-bottom:-1000px;
}
</style>
</head>
<body>
<div class="test">
<div class="left">左</div>
<div class="right">右<br>fdfd <br>hang <br>oooo</div>
</div>
</body>
</html>
效果：
总结：padding值可以被负的margin抵消掉；