Hi Piotr,
Sorry my site is on a bitnami install ...localhost.
I've added a screenshot and the source if that helps?
I've kept the header on the front page the original size and reduced the space below it using the code you supplied 'm3sman.
I've reduced the header size on the other 'pages'. You'll notice that on the screenshot.
The space I'd like to reduce is similar to the header space on .frontpage. The bit below the header.
The space is where I have put the black block.
Thanks,
John.