https://demo.cssworld.cn/4/3-2.php
<style type="text/css">
.parent{
width:500px;
text-align: center;
overflow: hidden;
}
.son{
float: left;
width: 250px;
margin-bottom:-99999px;
padding-bottom: 99999px;
}
.son:nth-child(1){
background: #7FFFD4;
}
.son:nth-child(2){
background: #CD5C5C;
}
span{
display: block;
}
</style>
<body>
<div class="parent">
<div class="son">
<span>1</span>
<span>1</span>
<span>1</span>
<span>1</span>
<span>1</span>
<span>1</span>
<span>1</span>
<span>1</span>
<span>1</span>
<span>1</span>
<span>1</span>
</div>
<div class="son">
<span>1</span>
<span>1</span>
<span>1</span>
</div>
</div>
</body>