Hi,
If you want to change the Style Sheet attached to a page on button click then i would suggest you make use of a small JS function. That should do the trick for you.
Link To the CSS
<link id="defaultStyle" href="styleSheet1.css" media="all" type="text/css" rel="stylesheet" />
Add this to your javascript Module.
function changeStyleSheet( styleSheetName ){
document.getElementById( "defaultStyle" ).href= styleSheetName ;
}
<input type="button" value="styleSheetName.css" onclick="changeStyleSheet( this.value )" />
BR//
Harsha