this been driving me crazy for the past week,

Ive been trying to swap the background placeholder for the header with a widgetContainer

i want to place a plugin i have to replace the background color/image while keeping the menu's overlaid on top

(ive tried everything; i cant get it to show behind everything; it remains stacked)

any ideas?

Seems a bit odd to try and place a widgetcontainer there... why not just add some PHP or JS to the theme itself to do this, it would be far easier.