SOURCE

console 命令行工具 X clear

                    
>
console
<div>
  <div class="float"></div>
  <div class="main"></div>
</div>
.float{
  width: 200px;
  height: 500px;
  background: skyblue;
  float: left;
}
.main{
  background: pink;
  height: 600px;
  overflow: hidden;/* 使其成为 BFC */
  
}