如何铺满整个屏幕和一直居中
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<style>
*{
margin: 0;
padding: 0;
}
.c1{
/* 100%;*/
/*height: 100px;*/
background-color: red;
position: fixed;
/*position: fixed;*/
top: 0;
right: 0;
left: 0;
bottom: 0;
}
.c2{
width: 600px;
height: 400px;
background-color: white;
position: fixed;
top: 50%;
left: 50%;
margin-top:-200px;
margin-left:-300px;
}
</style>
<title>工会公告</title>
</head>
<body>
<div class="c1"></div>
<div class="c2"></div>
<!--<p>sdd</p>-->
</body>
</html>