Edge Animate CC :: Can't Center Preloader In Browser Windows

I'm trying to center the preloader in the browser. this is a single full page animation.  I'm currently centering the stage using..
 
document.compositionReady...
sym.$("#Stage").css({"margin": "auto"})

which is working find for the stage but it doesn't cover the preloader. my preloader elements are "loaderbar" and "loading". URL... I tried....
 
<!--
<style>
#loader-bar { margin: auto; }
#loading { margin: auto; }
</style>
--> (without the comment tag)

in the header but it doesn't work for me. the loader is loading on the left of the browser window (full screen width is 1920) while the stage is loading in the center of the browser window. My stage size is 800x600. I tried including that in the css above but that didn't work either.