The problem comes from the fact that different browsers parse HTML and CSS differently. You can search on the internet for general tips on making your site displaying the same content properly on different browsers.
One of the most common problems is caused by using fixed width and height for elements of your page. A good way to fix this is by using percentages which automatically and more properly expands the elements of your page on the user’s screen.
If you want to see how your page displays across multiple browsers and operating systems without installing them, you will find the following third-party website very useful: http://browsershots.org/