Please help with frame size

[Tambel]

Please, help me with frames sizes. i get frame bottom,top,left,right values and screen size, but screen size value not in pixels, its float, width 0.87, heigth 0.42. (fullscreen mode) what it means? If it is relative values to real screen size, how heigth can be smaller than half of it real screen heigth?
I read that all frames margins are relative to screen size. So how i can apply frames margins to this screensize?

[ev0]

if it's anything like HTML/CSS you can use percentages, instead of exact pixels