HTML
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>原生多选 select 组件 - Select</title>
<link rel="stylesheet" href="https://cdn.w3cbus.com/library/mdui/1.0.2/css/mdui.min.css"/>
</head>
<body>
<div class="mdui-container">
<select multiple size="8" class="mdui-select">
<optgroup label="Fonts">
<option>Roboto</option>
<option>Calibri</option>
<option>Courier New</option>
<option>Verdana</option>
</optgroup>
<optgroup label="Size">
<option>50%</option>
<option>75%</option>
<option>90%</option>
<option>100%</option>
</optgroup>
<optgroup label="header">
<option>h1</option>
<option>h2</option>
<option>h3</option>
<option>h4</option>
</optgroup>
</select>
</div>
<script src="https://cdn.w3cbus.com/library/mdui/1.0.2/js/mdui.min.js"></script>
</body>
</html>