#back-top {float: right;}
#back-top a {
	width: 60px;
	display: block;
	text-align: center;
	font: 11px/100% Arial, Helvetica, sans-serif;
	text-transform: uppercase;
	text-decoration: none;
	color: #bbb;

	/* transition */
	-webkit-transition: 1s;
	-moz-transition: 1s;
	transition: 1s;
}
@media only screen and (max-width: 40em) {
	#back-top a  span{right: 20px;bottom: 10px;position: fixed;}
}
@media only screen and (min-width:40.0625em) and (max-width:64em) {
	#back-top a  span{right: 20px;bottom: 10px;position: fixed;} 
}
@media only screen and (min-width:64.0625em) {
	#back-top a  span{right: 90px;bottom: 10px;position: fixed;} 
}

#back-top a:hover {
	color: #000;
}

/* arrow icon (span tag) */
#back-top span {
	width: 50px;
	height: 50px;
	display: block;
	background: #ddd url(up-arrow.png) no-repeat center center;

	/* rounded corners */
	-webkit-border-radius: 99%;
	-moz-border-radius: 99%;
	border-radius: 99%;

	/* transition */
	-webkit-transition: 1s;
	-moz-transition: 1s;
	transition: 1s;
}
#back-top a:hover span {
	background-color: #777;
}