change the entire page background when I click on a button - css

Question

so here is my question:
lets say I have a page with 3 buttons. each contains a unique pattern as as background. I want to change the entire page background image once I click/ hover on one of the buttons.
what I need is something similar to http://subtlepatterns.com/
I dont need a stop preview option, as long as the background image change again when I select a different button.
how can I do that?
also, if its not possible, this will also work for me:
change the color of a DIV (instead of the entire page background) whenever I click/ hover on one of the buttons.

Answer 1

have 3 different body class in ur CSS sheet:
body.class1 {
background: ...;
}
body.class2 {
background: ...;
}
body.class3 {
background: ...;
}
use jQuery to dynamic change body class
$("#btn1").click(function() {
$('body').removeClass();
$('body').addClass('class1');
});
$("#btn2").click(function() {
$('body').removeClass();
$('body').addClass('class2');
});
$("#btn3").click(function() {
$('body').removeClass();
$('body').addClass('class3');
});
then finally put a id in each button to jQuery find this in DOM:
<a id="btn1">bg1</a>
<a id="btn2">bg2</a>
<a id="btn3">bg3</a>

Answer 2

Using just javascript you could do something like this
function changeBg(color) {
var color = '#' + color;
document.body.style.background = color;
}
http://jsfiddle.net/62SXu/
You can also change this to pass it the path to whatever your image is

Answer 3

does have to be done with CSS? it seems alot easier method to do with jQuery. something like this would work:
<style>
.button1 {background:url(url to PIC);}
</style>
$(document).ready(function (){
$(".onClick").click(function (){
var ID = $(this).attr("id");
$(body).removeClass();
$(body).addClass(ID);
})
})
<div class = "onClick" id="button1"> ... </div>
<div class = "onClick" id="button2"> ... </div>
<div class = "onClick" id="button3"> ... </div>