/*回到顶部*/
#back-top {
	position: fixed;
	bottom: 50px;
	right: 10px;
	opacity:0.75;
}
#back-top a {
	width: 108px;
	width: 32px\9;
	display: block;

	/* transition */
	-webkit-transition: 1s;
	-moz-transition: 1s;
	transition: 1s;
}
#back-top a:hover {
	color: #000;
}
/* arrow icon (span tag) */
#back-top span {
	width: 108px;
	width: 32px\9;
	height: 108px;
	display: block;
	margin-bottom: 7px;
	background:#ddd url(https://pic002.cnblogs.com/images/2011/36987/2011051823234124.png) no-repeat center center;
	background-color: transparent\9;

	/* rounded corners */
	-webkit-border-radius: 15px;
	-moz-border-radius: 15px;
	border-radius: 15px;

	/* transition */
	-webkit-transition: 1s;
	-moz-transition: 1s;
	transition: 1s;
}
#back-top a:hover span {
	background-color: #999;
        background-color: transparent\9;
}