<!DOCTYPE html>
<html>
<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>
<body>
<style>
*{
margin: 0px;
padding:0px;
}
.a{
width: 120px;
height: 120px;
background: red;
}
.b{
border: 1px solid;
margin: 10px;
}
</style>
<div>
<div>
头快坏了
</div>
</div>
</body>
</html>왜 이럴까요?
![[웹 프런트엔드] Node.js 빠른 시작](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
a,b 클래스는 안보이네요, 다시 보내주세요.