Sunflower orange tamplate's rounder corners

[cochlear]

The template's rounded corners seem to be purely CSS based without any use of corner image nor javascript. I think that's pretty clever. Anyone knows the name of the technique? I just need the name so I can find some explanations on Google (I looked at its sidebox style sheet and it's pretty hard to figure out what's going on).

http://(sorry, site offline)/137/ind...nflower_orange

[Ajeh]

Might download it and see ...

[Crooked_Halo]

How do I make my sidebox corners like the Sunflower Orange template designed by Vincent Wong? Any help would be greatly appreciated. (I am a total newbie, so be nice to me please)