browser resolution not native?

Ok I have been searching for the answer on this all day. Now I get the fact running browsers in full HD is a bit ridicules as everything would be too small. The res from guessing it like 500 x 300. I tried messing with font size and that does not help much. I can pinch zoom in but not out beyond the defult. Why is the resolution so large for browsers and can I change that?

 

turns our its aimed at some page value, if I move an active window to the right I can then zoom out to that view ( screen now show more of the page ) I must have this magic value set to less then the page its self. I dont know what the browsers use to determine the right end of the web page.