Add dark transparent background for video player timeline to increase visibility.

[Divzed]

Checklist

• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the request will be dismissed otherwise.
• This issue contains only one feature request.
• I have read and understood the contribution guidelines.

Feature description

Add the same dark transparent background under video player timeline as other video player buttons have already (speed/play/pause/mute).

Why do you want this feature?

• Increases visibility when playing certain videos.
• Looks better, matching video player current buttons.

Additional information