Same size for all Widgets

Hey guys,

I need your help:

I use several Widget boxes (literally just HTML text boxes in which I showcase Table Press Tables), my problem:

How can I set all Boxes at the same height? So that it is not content related, because that make the page look unorganized (see at the image: on the lower left you see that following boyes arent on the same level any longer)

http://www.ihlonline.de/img/icons/Bildschirmfoto%202013-09-14%20um%2011.06.13.png

Thank you in advance