Modern player SL 360 - seekbar, navigation and controls

Hello.

I’ve been tinking with the CSS of a published Modern player project with an image background with some success.  The Modern Player’s seekbar, controls and navigation buttons are seemingly hard coded to stretch 100% across the footer of the screen.  The Story Size height and width we use is 1334 x 750. 

Wondering if anyone has some code to share to set the seekbar, controls and navigation to sit within 1334px width.

Perhaps what I'm trying to achieve is not possible?

Thank you in advance.