Difficulty Centering Group of Buttons

I am designing a Joe Workman Screens site. I have had no problem centering my single-button using Screens Navigator. But, when I switch to “group of buttons” the buttons are no longer center aligned based upon the exact same settings. It’s not enough to say “50% from left (or right)”. I want the buttons centered according to page width but the settings say “the position as a percentage of the browser height from the left”. Why not a percentage of browser width from left (or right)??Regardless, how do I easily center a group of buttons using Screens Navigator? Thanks!

The “height” in the tooltip is obviously a typo.

The navigator alignment when using a group of buttons is, admittedly, a little more difficult than using a single button. The horizontal position you enter is the left hand edge of the up/down buttons. Because the buttons are scalable by the user this is the only absolute datum point.