CSS does not work for non authorised users

 hi all, im a bit of a novice with asp.net so the solution is probably glaringly obvious.
Basically all of the CSS styles for my pages have stopped working for non authorised users. the only page i have with general access is my login page. Im assuming this is because of the  <deny users="?"> line in the web.config file?. Ive tried adding a location for the css and setting that to general access:
<location path="~/styles/main.css">              
    <system.web>
      <authorization>
        <allow users="*"/>
      </authorization>
    </system.web>
  </location>

but the problem is still there. is there any way around this?
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