Why must border radius be 100%?


In HTML/CSS Unit 5, Sorting Your Friends, Q3 - why are you required to set the border to 100% to make a circle? "Set their border-radius to 100%. (Can you guess what this does before you look?)"

Surely the way to make a circle is to make the border radius 50% (i.e. the radius is half the height / width of the block?) A border radius of 100% makes no sense.

Can somebody please explain this?


because the person who created the course decided as such. Border-radius: 50% should also work in all major browsers