Following Lucas Gass advice on bug 37054#c51; related to bug 31327 and 38550: Right now we can change accent-color by changing hex values on a set of files (CSS/JSON/SVG). #408540 #006100 #418940 #418A40 #589D43 to a dark color (the difference on very similar shades of green seems to be a bug), and #6faf44 #71b443 #7cbb51 #dcefd0 to a light color. By default, using HSL model, the koha's green is around hsl(120, 40%, 40%). I would love to see a syspref to change that hue from 120 to any 0-255 value (or a nicer picker). This would apply to staff and OPAC, and could be overridden by a per library field or custom CSS. Not sure if this could be done independently of a per-user light/dark mode switch (bug 38550).