Hi Mike,
You should be able to increase the window size to the full width of your desktop by pressing the Maximize button. If that's not working, you can also click and drag the lower right hand corner of the window to resize it manually.
Some browsers offer a full screen mode, which can usually be accessed through the VIEW menu at the top left of the browser window (in some cases pressing the F11 key also works).
Hope that helps. Please let us know if you continue to experience a problem.