使用css3中的rgba:
r: red,取正整数或者百分数;
g:green,取正整数或者百分数;
b:blue,取正整数或者百分数;
a:alpha,取0~1之间的数
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>css3的rgba</title>
<style>
*{
padding: 0;
margin: 0;
}
body{
padding: 50px;
}
.mydemo{
padding: 25px;
background-color: red;
background-color:rgba(255,0,0,0.5);
}
.mydemo p{
color: black;
}
</style>
</head>
<body>
<div class="mydemo">
<p>myIp</p>
</div>
</html>

