Maybe I'm just extremely unlucky but none of the test messages I sent had a darker username colour meaning I couldn't check the appearance of how the white outline appears
I've now realized that since slime2 sets the colorBrightness level, the color brightness isn't correctly set for dark colors in DEFAULT_USER_COLORS. I'm going to update it so that slime2 no longer handles that, and instead that'll be handled from within base.js itself.