Change Web screen Resolution

Question

Hi,
I have created a web system and set the width and height of each page to 100% vis CSS. Setting the height and width to 100% ensures every web page auto fits to suit different screen resolutions in visual studios. However, when I publish the system to the server the screen resolution seems to ignore the CSS. I was wondering if anyone knows why this is happening or if there is a way to programme the systems resolution in c#.

Many thanks for your help.