Hero Image Question

Question

https://www.w3schools.com/howto/howto_css_hero_image.asp

On this website guide, the code shows that the Html and body element needs to have 100%. I don't understand why??
Shouldn't the body element by default take up 100% height or width of the screen???

Answer 1

I don't want to copy and paste and act like I know what I'm talking about lol, but this page explains it. I give credit to the author. There is an aside area on the page where you can give him thanks.

https://makandracards.com/makandra/39473-stretching-an-html-page-to-full-height