The QuickJava add-on for Firefox lets you add toolbar button to toggle CSS (and other features) on and off.<p><a href="https:&#x2F;&#x2F;addons.mozilla.org&#x2F;en-US&#x2F;firefox&#x2F;addon&#x2F;quickjava&#x2F;" rel="nofollow">https:&#x2F;&#x2F;addons.mozilla.org&#x2F;en-US&#x2F;firefox&#x2F;addon&#x2F;quickjava&#x2F;</a>