Hi,
To improve the roundcube interface, I create 2 years ago a new theme.
I have done a lot of correction and improvement in recent months
I think it is now mature enough to share it here.
github com/seb1k/Elastic2022 (as new user, i can’t write the full link)
It may be displayed first as “beta” in the “roundcube skin selection” and later as “default” skin.
Feel free to try it and maybe include it to Mail in a Box 
