The adress is www.e-stoodzin.pl
It would be hard to install the mod incorrectly because it is only about overriding the html_header.php file What I noticed is that only some of the changes I made to the css files are being processed at the page itself- for example font colors, except on the main page.

The cache and cookies were deleted before the changes.

I am rather sure, that the index page css file is named incorrectly, but I have no idea what should be the right name of it.

BTW, there is also a huge white space to the right from the actual content of the page. Any idea how to get rid of it?

Thanks for the reply :)