<html>
<head>
<title></title>
<meta charset="utf-8" />
<link rel="stylesheet" href="style.css"/>
</head>
<body>
<script>
function fun() {
document.querySelector('.plus').style.transform = 'rotate(50deg)';
}
</script>
<div onclick='fun();'>click</div>
<b class='plus'>+</b>
</body>
</html>
Простой
Средний
