How to change a video player's background color?

Question:
Does anybody know how can I change a background/border color of the video player?

Product:
Wix studio

What are you trying to achieve:
I’m trying to emulate a gallery using some repeaters and I’ve had to use a video player instead of a video asset due to repeater compatibility. The only thing that’s bothering me is that I can’t change the colour of the background or outline of my video player. Black is the default colour, but I want to change it to white.

What have you already tried:
I’ve tried changing the container sets, the section, the slideshow repeater, the video player itself in the side panel and nothing seems to work.
I don’t know much about programming, but I’ve even tried overwriting the video player’s css information and it doesn’t work either.

.video-player {
background-color: white;
border: white;
object-fit: fit;
}
.slideshow {
background-color: white;
}

Additional information:
help! Example: