child theme different to parent: because of update?

Hey!
I really don’t get why my new child theme looks different to its parent when I go on “live preview”. The layout is similar, but only the middle part of the page is there, left and right sides went missing somewhere. The top navigation bar is missing as well.

Can this be because the child’s template (retro-fitted) has been updated? (I am still using the older version on my blog and created a child based on this one)

[ Please do not bump, that’s not permitted here. ]