How can I take control over html background?

Thanks Milton. I didn’t get to use this solution after all. What I did was use scalemode HEIGHT_CONTROLS_WIDTH and reposition/rescale everything. The client wanted a responsive UI, so I couldn’t use FIT mode because I wouldn’t be able to reach the edges of the screen to place a button on the top right corner for example.

However I will keep this solution in mind and use it when possible.