/**
 * borrowed from http://www.hunlock.com/blogs/Totally_Pwn_CSS_with_Javascript
 */
function getCSSRule(ruleName, deleteFlag) {               
   ruleName=ruleName.toLowerCase();                       
   if (document.styleSheets) {                            
      for (var i=0; i<document.styleSheets.length; i++) { 
         var styleSheet=document.styleSheets[i];          
         var ii=0;                                        
         var cssRule=false;                               
         do {                                             
            if (styleSheet.cssRules) {                    
               cssRule = styleSheet.cssRules[ii];         
            } else {                                      
               cssRule = styleSheet.rules[ii];            
            }                                             
            if (cssRule)  {                               
               if (cssRule.selectorText.toLowerCase()==ruleName) { 
                  if (deleteFlag=='delete') {             
                     if (styleSheet.cssRules) {           
                        styleSheet.deleteRule(ii);        
                     } else {                             
                        styleSheet.removeRule(ii);        
                     }                                    
                     return true;                         
                  } else {                                
                     return cssRule;                      
                  }                                       
               }                                          
            }                                             
            ii++;                                         
         } while (cssRule)                                
      }                                                   
   }                                                      
   return false;                                          
}                                                         

function killCSSRule(ruleName) {                          
   return getCSSRule(ruleName,'delete');                  
}                                                         

function addCSSRule(ruleName) {                           
   if (document.styleSheets) {                            
      if (!getCSSRule(ruleName)) {                        
         if (document.styleSheets[0].addRule) {           
            document.styleSheets[0].addRule(ruleName, null,0);      
         } else {                                         
            document.styleSheets[0].insertRule(ruleName+' { }', 0); 
         }                                                
      }                                                   
   }                                                      
   return getCSSRule(ruleName);                           
} 

cache=[
    [],[]
];

function setBG(cls, val)
{
    cls = cls.split(' ');
    for (i=0;i<cls.length;i++) {
        c = cls[i];
        if (cache[i][c] == null)
            cache[i][c] = css = addCSSRule("." + c);
        else
            css = getCSSRule("." + c);
        css.style.background = val;
    }
}

function hilight(obj) {
    setBG(obj.className, "red");
}

function dehilight(obj) {
    setBG(obj.className, null);
}