Following up on the reply on your website. Thanks for your quick reply.
I tested the code you provided and indeed it works. Btw, by means of testing I applied it in the Theme options >> custom css and it works even from there. I have to do some more thorough testing in order to check if everything else is still correct, but it looks promising.
Regarding the tagline displayed over multiple lines when the searchbox is removed (via the theme options), please have a look at this site.
PS. I know I should not use IE7, unfortunately a large part of the world still doesn't :-(