解决方案
overflow:hidden代码如下：
<style type="text/css">
.father {
width: 200px;
height: 200px;
background-color: #0066CC;
margin-top: 200px;
/* border: 1px solid transparent; */
/* padding: 1px; */
/* overflow: hidden; */
}
.son {
width: 100px;
height: 100px;
background-color: #9B0909;
margin-top: 50px;
}
</style>
<body>
<div class="father">
<div class="son"></div>
</div>
</body>
原文：https://www.cnblogs.com/wuxiaoshi/p/13184673.html