So I changed my logo in the top left of the page. Initially I had it pretty big which was 800 x 300 pixels. My logo designer finally finished my logo which is 220 x 60 pixels which was uploaded to the site using the same filename logo.gif.

The problem I have is that the only way to make it show is to clear the firefox cache. Some of my customers are emailing to let me know that there is a void in the space between the logo and header. I told them to clear the cache but some cannot as they need their cache for other purposes.

Is their a css or code to put inside to force refresh the new log and layout being displayed correctly?