代碼
提交代碼
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=`, initial-scale=1.0">
<title>Document</title>
<style>
.demo>.demo:only-child{
color:#fff;
background: red;
padding:10px;
}
</style>
</head>
<body>
<body>
<div class="demo"> 慕課網(wǎng)
<div class="demo"> 慕課網(wǎng) </div>
</div>
</body>
</body>
</html>
運行結(jié)果