code：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>user-select</title>
<style type="text/css">
div { width: 200px; height: 70px; padding: 10px; border: 1px solid #000; background: #eee; margin-top: 20px; overflow: hidden; }
.none { user-select: none; }
.text { user-select: text; }
.all { user-select: all; }
.element { user-select: element; }
</style>
</head>
<body>
<h1>user-select: none;</h1>
<div class="none">none</div>
<h1>user-select: text;</h1>
<div class="text">text</div>
<h1>user-select: all;</h1>
<div class="all">all</div>
<h1>user-select: element;</h1>
<div class="element">element</div>
</body>
</html>