I already had a solution for changing the proportions of the left and right panel dynamically, but it broke with the release of WEBCON BPS 2025.
I've reviewed it and improved it a little bit. There are now 2x4 options:
and the other way around for the right panel.
You can find the CSS definition in this post.
If you are not yet using WEBCON BPS 2025, you may combine the constant approach with the CSS for the 'old UI'