var dom = (document.getElementsByTagName) ? true : false;
var ie5 = (document.all) ? true : false;

function mon(obj) {
   if ( ie5 ) { 
     obj.style.background=document.styleSheets[0].rules[2].style.background;
//     obj.style.color=document.styleSheets[0].rules[1].style.color;
   }
   else if ( dom ) {
     obj.style.background=document.styleSheets[0].cssRules[2].style.background;
//     obj.style.color=document.styleSheets[0].cssRules[1].style.color;
   }
   
}

function moff(obj) {
   if ( ie5 ) { 
     obj.style.background=document.styleSheets[0].rules[3].style.background;
//     obj.style.color=document.styleSheets[0].rules[2].style.color;
   }
   else if ( dom ) {
     obj.style.background=document.styleSheets[0].cssRules[3].style.background;
//     obj.style.color=document.styleSheets[0].cssRules[2].style.color;
   }           
}