等高布局

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；