Since display of the test wiki is probably browser dependant I have a here a MSIE screen shot

http://members.chello.nl/epzachte/Wikipedia/Temp/HeaderSizes.png

Can you spot without an eye blink which header is ==, which === and which ==== ?

Here is an alternative (4 levels) without reverting to those oversized fonts:

http://members.chello.nl/epzachte/Wikipedia/Temp/HeaderSizes2.png

Erik Zachte