#back-top {
	width: 12px;
	height: 12px;
	right: 50px;
	bottom:100px;
	padding: 16px 13px 10px;
	cursor:pointer;
	text-align: center;
	border-radius: 5px;
	position: fixed;
	display: none;
	color: #fff;
	background: rgba(0, 0, 0, .4);
	z-index: 10000;
}

#back-top:hover {
	background: rgba(0, 0, 0, .5)
}

.back-top-icon {
	display: block;
	width: 12px;
	height: 12px;
	border: 2px solid #fff;
	border-right: 0;
	border-bottom: 0;
	transform: rotate(45deg);
	-moz-transform: rotate(45deg);
	-ms-transform: rotate(45deg);
	-webkit-transform: rotate(45deg);
	filter: progid:DXImageTransform.Microsoft.Matrix(sizingMethod='auto expand',
		M11=0.70711 , 
		M12=-0.707 11 , 
		M21=0.707 11 ,
		M22=0.70711)";  /*ie兼容旋转*/
}