Thanks for your response. I added those lines to the respective areas of the CSS pages, but unfortunately that didn't seem to do the trick.
Maybe I did not explain myself properly (which im good at doing lol).
I have included screenshots to explain the problem
Screenshot1: Everything looks fine when the browser window is maximised
Screenshot2: The main content (surrounded by the thin red border) has been moved to under the navigation bar, when the browser window is made smaller.
I would like to be able to keep everything in place as it is when the browser window, and if the browser window becomes smaller, i would still like everything to remain in place.
I hope that clears it up