The page got a few HTML errors it seems. Is it perhaps the <script> tag between <head> and <body> that causes the behaviour that you call ‘breaking the header’?
If the problem isn’t caused by that, I think the community needs a bit more information to provide meaningful help. Have you looked at requesting help? That topic has some good suggestions that make it easier for us to help you. With better information I think you can get a good solution much quicker.