Floating DIVs problem

I have problems with DIVs across a page (the main content plus a sidebar on each side) not aligning in Dreamweaver itself but mysteriously appearing OK in browsers on both platforms. Can you help? I am sure it is "easy" - I just can't figure it out :(.

The site is here: http://www.centralbaptistkindergarten.org.nz/
The css is here: http://www.centralbaptistkindergarten.org.nz/css/cbk.css

Many thanks for your help!

Best

Anne
New Zealand