/*
.mainbg
{
	background: url('http://www.atefa.net/images/photos_bg2/16.jpg') no-repeat center center fixed;
	
	-webkit-background-size: cover;
	-moz-background-size: cover;
	-o-background-size: cover;
	background-size: cover;
	
	-khtml-opacity:0.8; 
	-moz-opacity:0.8; 
	-ms-filter:"alpha(opacity=80)";
	filter:alpha(opacity=80);
	filter: progid:DXImageTransform.Microsoft.Alpha(opacity=0.8);
	opacity:0.8; 
	
	background-blend-mode: overlay;
}
*/