A developer shares lessons learned while adding colorblind support to their Belgian Wage Calculator. Testing with Firefox's "Let's get colorblind" extension revealed how red/green colorblindness distorts UI colors.

Most screen colors collapse to yellow/blue shades under full red or green colorblindness. Contrary to assumptions, shifting hues didn't solve contrast issues—users still saw indistinguishable palettes.

The solution involved two toggleable modes: one for deuteranopia and one for protanopia. Light/dark gradations replaced hue-based distinctions. Surprisingly, the red mode also helped some green colorblind users.

Final UI uses clear +/− indicators for data values. Real-world feedback remains key—the developer encourages actual colorblind users to test and report issues with the new accessible interface.