Position of the autocomplete suggest box

Hey,

I am new to jQuery and very proud to get the autocomplete widget runnig on my site.
My problem is now: I don't know how I can position the suggestion box. As you can see, the box need an offset of one Pixel to the left.

I play around with position and offset, but I don't get it. So maybe someone could point me in the right direction.

Thanks in advance.

Stefano