a.back-to-top {
	display: none;
	width: 40px;
	height: 40px;
	text-indent: -9999px;
	position: fixed;
	z-index: 999;
	right: 20px;
	bottom: 20px;
	background: #27AE61 url("img/up-arrow.png") no-repeat center 43%;
	-webkit-border-radius: 20px;
	-moz-border-radius: 20px;
	border-radius: 20px;
}
a.left-back-to-top {
    display: none;
    width: 40px;
    height: 40px;
    text-indent: -9999px;
    position: fixed;
    z-index: 999;
    left: 20px;
    bottom: 20px;
    background: #27AE61 url("img/up-arrow.png") no-repeat center 43%;
    -webkit-border-radius: 20px;
    -moz-border-radius: 20px;
    border-radius: 20px;
}
a:hover.back-to-top {
	background-color: #000;
}
a:hover.left-back-to-top {
    background-color: #000;
}