background:url("/images/nav.png") no-repeat center center rgba(0, 0, 0, 0);
-webkit-background-size: 17px 17px; //webkit support
-moz-background-size: 17px 17px; //Mozilla support
-o-background-size: 17px 17px; //Opera support
background-size: 17px 17px;

background-size: 17px 17px;

background:url("/images/nav.png") no-repeat scroll center center rgba(0, 0, 0, 0);
background-size: 17px 17px;