CSS-customisation and cross-browser functionality of a PHP based WIKI

I have a (pmwiki-based) website already working, but **the skin is not well set**. **The pages do not fill in the full screen as I increase screen resolution.** The task is to make sure that the pages appear correctly in all browsers and all screen resolutions ## Deliverables I have a php-based website (wiki) already working. The layout is set by a skin written css. Today there are ares not covered by anything if I increase sceen resolution. If you know some css (hopefully) it might not be too complicated to set which window how should appear. I'm very basic in CSS and I have problems to understand how is the CSS file used by the php core software. The task is to make sure that the pages appear correctly in all browsers and all screen resolutions See also attached file