newbie css

body {    background: url(images/baseball_diamond.jpg) no-repeat center center fixed;    -webkit-background-size: cover;    -moz-background-size: cover;    -o-background-size: cover;    background-size: cover;    height: 100%; }   html {  	height: 100%; }  #pagewrapper { 	min-height: 100%; }  #main-content { 	width: 924px; 	overflow:auto;	padding-bottom: 150px; 	background-color: #fff; 	opacity:0.9; 	filter:alpha(opacity=90); /* IE 8 and earlier */ }  footer { 	position: relative;	margin-top: -150px; /* negative value of footer height */	height: 150px;	clear:both; 	background-color: #fff; 	opacity:0.8; 	filter:alpha(opacity=80); 	clear: both; }/*Opera Fix*/body:before {	content:"";	height:100%;	float:left;	width:0;	margin-top:-32767px;/}