Resizing browser window horizontally does not cause website to resize properly; no scroll bar either.

When I resize my browser window in the horizontal direction, the contents of the web page do not resize appropriately. No scroll bar shows up either to scroll left/right. For example:, I can be displaying 1920 pixels horizontally while the frame on the website is centered and only 800 pixels wide. As I resize from right to left, the frame will not slide over accordingly to stay centered as it usually would. Thus if I resize from right to left all the way to the center, the whole right half of the frame will be cut off with no way to even scroll over if I wanted to. Still don't understand my problem? Consider that this very support website we are using, displayed at 1080p, does not take up the full width of the screen. Now start resizing your screen from right to left. Notice how the active part of the website switches position? This does not happen for me. How do I fix this so horizontally scrolling/resizing is normal? Thanks!