CÓDIGO BG

CSS!

/* CSS Document */
body {
background-image: url(#####BG 1#####);
background-repeat: no-repeat;
-moz-background-size:100%;
-webkit-background-size:100%;
background-size:100%;}
div, html, body, p, ul, ol, li, a, form, img, table, td, h1, h2, h3, h4, h5, h6, blockquote, header, section, footer, aside, nav, article, figure, figcaption, dl, dt, dd {margin:0;padding:0;}
header, section, footer, aside, nav, article, figure, figcaption {display: block;}
table {border-collapse:collapse;}
img {border:none;}
ul, li {list-style:none;}
input:focus, textarea:focus {outline:none;}
a:link,a,a:hover,a:active{outline:none;}

____________________________________

CÓDIGO!

<script language="JavaScript">
var quotes=new Array()
quotes[0]='<link rel="stylesheet" href="#####CSS 1#####">'
quotes[1]='<link rel="stylesheet" href="#####CSS 2#####">'
var whichquote=Math.floor(Math.random()*(quotes.length))
document.write(quotes[whichquote])
</script>

- Jonathan Fonseca @bypikeno