1、margin塌陷bug
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<style>
*{
margin: 0;padding: 0;
}
.wrapper{
margin-left: 100px;
margin-top: 100px;
width: 100px;
height: 100px;
background-color: blue;
/* border-top: 1px solid red; //手法不专业，太残暴*/
overflow:hidden; /*推荐方式*/
}
.content{
margin-left: 50px;
margin-top: 50px;
width:50px;
height: 50px;
background-color: green;
}
</style>
<body>
<div class="wrapper">
<div class="content"></div>
</div>
</body>
</html><!DOCTYPE html>
<html lang="en"
