I'm a p element within the main element. The main element's font size is 40px, making me 40px.
I'm a p element with a font-size of 16px. Pixels are a fixed-size unit that won't change relative to the main's font-size. Try changing the font-size of the main element to see what I mean!
I'm a font size of 2em, which will equal 80px since I'm in the main tag (40px x 2).
I'm a font size of 50%, which will equal 20px since I'm in the main tag (40px x 50%)