demo.html:
<!DOCTYPE html>
<html >
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
span {
border: 1px solid #000;
}
span::before {
content: attr(data-text); /* 僞元素通過attr()擷取标簽自定義屬性的值 */
}
</style>
</head>
<body>
<span data-text="aaa">bbb</span> <!-- data-text标簽自定義的屬性 -->
</body>
</html>