Obnoxious YouTube layout is not sizeable

Can not find a way to resize the video space. There is no size other than too large.
I rarely use full screen or zoom, and there is no other choice. The video uses too much space.
It starts out the normal size I use, then expands. After expanding the space for the video, the video goes beyond the margin. I keep my browser at a useful size for me. However it is necessary to resize it because the video space will not adjust to the size available like in past layouts. Then everything is too large - in-your-face size that can not be adjusted. Is the space adjustable like in past layouts?

Additionally, where is the thumbnail for the suggestion column on the side of the video space?
The graphics in the suggestion column are are also huge, and not resizable.
Really tired of the in-your-face sizing that does nothing but waste space and affect efficiency.

Is there a solution? Am I not finding the resizing features or do they not exist?

The issue names no file, test, or entry point. Reproduce the YouTube video and suggestion-column sizing in the extension, then trace the relevant frontend layout behavior. Done means the video and suggestion thumbnails fit the available browser space and can be resized without unwanted expansion.