我该如何改变一个div背景的透明度,而不影响文本或其内部任何内容的透明度?
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<div class="bg">
<h1>welcome</h1>
<p>Hello world. Welcome to my site</p>
</div>
</body>
</html>
<style>
.bg{
background-color: black;
color: #ffffff;
}
</style>