Controlling background color of start screen?

[Felix E. Klee]

For testing, I installed an [early preview][1] to my web app using
Firefox Aurora on Android. A shortcut on the home screen has been
created.

When I tap that shortcut, then first I see a start screen with the app's
icon and a load animation (spinning circle). The background color of
this screen seems to vary from app to app. In the case of my app, it's
an ugly yellowish green.

How is the background color of that start screen determined?

Can the start screen's background color be specified, e.g. via the web
app's manifest?

[1]: http://sq.rotogame.com/install-webapp

[Felix E. Klee]

Because [my phone's][1] memory was full, I cleaned Aurora's data and
reinstalled my web app. Now the background in the start screen is black,
which is perfect!

I still don't understand, though, why earlier I got that ugly yellowish
green as background color. The very first test install of the app was
with an icon that had a background color, though not that one. But maybe
there's a relation.

Anyways, for me the problem seems solved.

[1]: http://en.wikipedia.org/wiki/Huawei_Sonic