How to use conditional CSS for IE browser in drupal6?

I have one file css_browser_selector.js file in sites/all/js and the code of that file is as given below:

 function css_browser_selector(u){var ua=u.toLowerCase(),is=function(t){return ua.indexOf(t)>-1},g='gecko',w='webkit',s='safari',o='opera',m='mobile',h=document.documentElement,b=[(!(/opera|webtv/i.test(ua))&&/msie\s(\d)/.test(ua))?('ie ie'+RegExp.$1):is('firefox/2')?g+' ff2':is('firefox/3.5')?g+' ff3 ff3_5':is('firefox/3.6')?g+' ff3 ff3_6':is('firefox/3')?g+' ff3':is('gecko/')?g:is('opera')?o+(/version\/(\d+)/.test(ua)?' '+o+RegExp.$1:(/opera(\s|\/)(\d+)/.test(ua)?' '+o+RegExp.$2:'')):is('konqueror')?'konqueror':is('blackberry')?m+' blackberry':is('android')?m+' android':is('chrome')?w+' chrome':is('iron')?w+' iron':is('applewebkit/')?w+' '+s+(/version\/(\d+)/.test(ua)?' '+s+RegExp.$1:''):is('mozilla/')?g:'',is('j2me')?m+' j2me':is('iphone')?m+' iphone':is('ipod')?m+' ipod':is('ipad')?m+' ipad':is('mac')?'mac':is('darwin')?'mac':is('webtv')?'webtv':is('win')?'win'+(is('windows nt 6.0')?' vista':''):is('freebsd')?'freebsd':(is('x11')||is('linux'))?'linux':'','js']; c = b.join(' '); h.className += ' '+c; return c;}; css_browser_sele开发者_JS百科ctor(navigator.userAgent);

I have applied different css on different browsers using class of that browser from the code written above. The code is working for every browser but its not working on IE6, IE7. There are two default files of ie6 and ie7 in Drupal 6 but these files are also not working. I dont know how to make changes in IE browser.

Thanx in advance.

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Use .ie6 before element of Css for ie6 like.ie6 #id { margin-left:23px; } this code work for i6 only