issue board list widths customizable
Description
When having more than 4-5 columns in the issue board, vertical scrolling is necessary. It would be nice to be able to customize the column widths, or at least make them somewhat responsive. Having 6 columns in 1280px screen, still leaves for about 200px per list, which is really enough. Now, apparently, max-with and min-with are both set to 400px (for screens >768px).
Proposal
Making list/column widths customizable or more responsive (although this may be a little trickier, since lists with no issues may be smaller than the ones with issues, if one is using min-with and max-width together with flex box model).