<!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>
<body>
<div class="add"></div>
<style>
.add {
border: 1px solid;
width: 100px;
height: 100px;
color: #ccc;
transition: color .25s;
position: relative;
}
.add::before {
content: '';
position: absolute;
left: 50%;
top: 50%;
width: 80px;
margin-left: -40px;
margin-top: -5px;
border-top: 10px solid;
}
.add::after {
content: '';
position: absolute;
left: 50%;
top: 50%;
height: 80px;
margin-left: -5px;
margin-top: -40px;
border-left: 10px solid;
}
.add:hover {
color: blue;
}
</style>
</body>
</html>
