SOURCE

<h2>3行框让出位置</h2>
<div style='width:200px;height:200px;border:1px solid blue'>
  <div style='width:100px;height:100px;border:1px solid red;float:left'></div>
  <span>我是行框</span>
</div>

<h3>3.1行框让出位置,但是第一个词太长</h3>
<div style='width:200px;height:200px;border:1px solid blue'>
  <div style='width:100px;height:100px;border:1px solid red;float:left'></div>
  <span>longggggggggggggg 红色float框右侧无法容纳长单词所以被挤下来了</span>
</div>