Ok, no problem. Do this:
1 - Open the CSS file \Portals\_default\Skins\Stronghold\styles\style.css
2 - Find this 'min-height: 400px;' (remove the quotes to search)
3 - Change 400px to, let's say, 200px - This will make the vertical space shorter.
4 - Save the file.
5 - Change to another number if you need.
This should do it.
Cheers,
Aderson