How is it still not possible to define percentage sizes for elements?

So many websites out there use percentages to define the height of main elements and sections on their websites. I want my website’s first section to have fullscreen visibility across all screen resolutions. In CSS this is extremely easy; just set the height of the element to 100% or ‘vh’ (viewport-height) or whatever it is called. I really hope to see this feature soon - if not in the editor, then through WIX code.

Cheers
Oliver

Or maybe it’s HTML where i can define 100% vh normally, I’m not sure - I just remember it being easy - I don’t code that much anymore.