MS Edge (chromium) picture-in-picture player style..

[VitalSkib]

Please change the view of the picture-in-picture player, just like in the MS Edge, with rounded corners and a 1px thin border. . I tried it on my own but failed, due to a lack of knowledge. Thanks in advance.

MS Edge pip player is on the right, and my attempt on the left.. I just did not find a way how to get rid of the background with square corners (green in this case).