背景虚化

-webkit-filter: blur(5px);
   -ms-filter: blur(5px);
   filter: blur(5px);
   filter: progid:DXImageTransform.Microsoft.Blur(PixelRadius=5,MakeShadow=false);
   z-index: 50;
   background-position: center 0 !important;
   background-repeat: no-repeat;

bilibili背景处理方法。

<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			.box{
				 100px;
				height: 100px;
				background: #fff;
				position: relative;
				margin: 0 auto;
			}
			.box2{
				position: absolute;
				left: 0;
				top: 0;
				 100%;
				height: 100%;
				background:#000;
				opacity: 0.3;
			}
			.row {
				-webkit-filter: blur(3px);
				-moz-filter: blur(3px);
				-o-filter: blur(3px);
				-ms-filter: blur(3px);
				filter: blur(3px);
			}
			.box3{
				50px;
				height: 50px;
				background: #fff;
				margin: 0 auto;
				position: absolute;
				left:25px;
				top: 25px;
			}
		</style>
	</head>
	<body>
		<div class="box ">
				<div class="box2"></div>
				<div class="row">
					1231321
					2132
				</div>
				<div class="box3">
					<p>123</p>
				</div>
		</div>
	</body>
</html>