<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
div {
width: 100px;
height: 30px;
border: 1px solid red;
margin: 100px auto;
position: relative;
}
div::after {
content: "";
width: 10px;
height: 10px;
border-right: 1px solid red;
border-top: 1px solid red;
position: absolute;
top: 10px;
right: 10px;
transform: rotate(45deg);
}
</style>
</head>
<body>
<div></div>
</body>
</html>
