#怎么让红色把两边填满，还有上面也不要露出来，好像是外边距和外边框的事，求教怎么弄
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="applicable-device" content="pc,noblie">
<title>Name</title>
<meta name="keywords" content="">
<meta name="description" content="">
<style>
body { background-color:rgba(214, 214, 214, 0.445); }/*灰色背景*/
ul li { list-style: none; }
.topbar {
width: ;
height: 66px;
background-color: red;/*纯白底white*/
}
</style>
</head>
<body>
<div class="topbar"></div>
</body>
</html>
