[FEATURE_REQUEST] --content-max-width via gui/conf

[CrazyWolf13]

Is your feature request related to a problem? If so, please describe.

I really like the idea of #1463 and I'd love to see this implemented.

Custom CSS is nice, however most of the time a user will not find this by itself, so via gui/conf would be much better.

Describe the solution you'd like

Maybe I once have some time to look into this myself.

Priority

Low (Nice-to-have)

Is this something you would be keen to implement

Yes!