How can we achieve the same zoom effect on yahoo.com?

go to yahoo.com and with firefox ctrl + +

as you can see the page zooms very nicely, anyone has idea how they achieved that?

edit:
just realized that msn also has the same effect, but google is messed up

just realized that msn also has the same effect, but google is messed up

and page does that, try it here. I believe its just a browser shortcut

It is definitely browser functionality.

define all sizes in relative values

This is browser hot keys to increase font size, yahoo has everything relatively so byt increasing font u automatically increasing everything else, tables, divs ..