<!DOCTYPE html>
<html>
<head>
<style>
h1 {
border-left-style: double;
}
div {
border-style: solid;
</style>
</head>
<body>
<h1>带有双左边框的标题</h1>
<div> 具有双左边框的 div 元素。</div>
</body>
</html>