Seperate CSS files for Firefox versions

Have you come across UI issues in different versions of Firefox?

we can call different CSS files for different versions of firefox using  jquery/javascript - 

var version=jQuery.browser.version;
     if (jQuery.browser.mozilla) {   
           var verarray=version.split('.');
           if(verarray[0]=='1' && verarray[1]=='9' && verarray[2]=='2')
           {
                var head= document.getElementsByTagName('head')[0];
                var addCSS= document.createElement('link');
                addCSS.href = 'css/CSIdentity.ff3.6.css';
                addCSS.rel = 'stylesheet';
                addCSS.type = 'text/css';
                head.appendChild(addCSS);
           }    
     }