Maximenu submenu item moved outside in the left

Hi, i have bought params plugin form Joomla 2.5 CK menu

i am playing with submenu items(showing modules etc.
But if you look on my test site web.qtd.cz/
3. main item Demorrom, if you pick mouse over, you will see that submenu item is with part of it width outside of page.

I tried to leave submenu item style width in main item blank, and style it with field Horizontal gap for sublevel, but background is only around width of main item, so i filled width 900px but then is submenu moved to the left and part is outside of the page
if submenu width is filled, horizontal gap is not reflecting filled value

Hi
deactivate the option "overflow detection" in the effect options of the module
CEd