代码编辑器：
x
1
2
<meta charset="utf-8">3
<link href="/static/next/css/tryit.css?v=2017082407" rel="stylesheet"/> 4
<style>5
#main {6
display: flex;7
flex-direction:column;8
}9
10
#main div {11
width: 40px;12
height: 40px;13
}14
</style>15
16
<div id="main">17
<div style="background-color:coral;">A</div>18
<div style="background-color:lightblue;">B</div>