Why would my site change sizes from testing offline to uploading it?

Question

I am building a new site, and I have a folder on desktop with everything in it. For testing basically I open the index page in a browser and preview that way while building it. It looked correct in firefox, safari, chrome and opera on my mac. I uploaded that file to the server, and now firefox on mac displays everything much smaller. Like all size decreased by 200px in width and fonts got small too. The other mac browser show it fine. I had 4 style sheets at first, a main one then separate ones for other pieces, I combined all into one still no change. Initially I reset font to 100% and then set a base font of 62.5% and adjusted sizes with em's. Someone said that could be culprit so I tried changing to pixel values. No change.
Any idea what I can check why it only changes in one?
Thank you.

Answer 1

The web version could be cached. Try deleting it!

Answer 2

Is it possible that you just changed the zoom on the browser?

Reset it in view->zoom->reset

Answer 3

Make sure that the off-line local copy is still in the same condition as you left it. Then delete all the uploaded files from your webserver, and replace them with the desktop files.

There's a chance that, as Fiarr suggested, your browser is doing something weird with the cache, so ctrl+F5 to deal with that. Goog's suggestion of the zoom being different for your online site is probably the best, but, just to be sure, use Firebug to see what's happening and where the crazy-styling is coming from.

Failing that, you might consider posting a link to your site so that we can see what's actually happening, rather than guessing.