(function getStyles(){var CSSrules,allRules,CSSSheets, unNeeded, currentRule,isHover;
CSSSheets=document.styleSheets;

for(j=0;j<CSSSheets.length;j++){
    for(i=0;i<CSSSheets[j].cssRules.length;i++){
        currentRule = CSSSheets[j].cssRules[i].selectorText;
        isHover = currentRule.indexOf(":hover")==-1?true:false;
        if(!document.querySelectorAll(currentRule).length){ 
           if(isHover){
                unNeeded+=CSSSheets[j].cssRules[i].cssText+"<br>"; 
        }
    }       
 }
}

docBody=document.getElementsByTagName("body")[0];
allRulesContainer=document.createElement("div");
docBody.appendChild(allRulesContainer);
allRulesContainer.innerHTML=unNeeded;

return false
})()

Ever wanted to clean out your style-sheets from unneeded styles?

Open firebug and paste in this function in the console and click run.

You will see that in the bottom of the page there will be a list of all styles that where not applied.