Do we really need this strong dark border? For text I get it, but I don't think the border looks good... It's even more noticeable when you have a messagebox on the same page:

Also, the title and description text of such a box now looks exactly the same... shouldn't the latter use the secondary color? If this violates WCAG contrasts, maybe making the background of these boxes a bit lighter would be a good alternative?

(FWIW the border colors were slightly different before, but not as strongly)

The border being the same as the main color is simply how it was before, I didn't change that. It doesn't have to be as pronounced as far as WCAG goes.

If by "look exactly the same" you mean they have exactly the same color, yes, that's the default text color in both cases. Technically you can make the title have secondary text color (dark grey) but then you get a wonky case where the title is lighter than the text but not colored, which I think is even weirder. Since the title is already bold, I think it has enough emphasis to not be mistaken as part of the text that follows.

As for just making the background lighter, that won't really help that much. Most of the colors would be too light even on a white background.

@marinaej Since I cannot reply to your comments directly for some reason, I'll comment here. The blue in particular was aligned with the theme color. For other colors, I used the existing colors as the starting point and used the contrast calculation in the dev tools to calculate the optimal contrast. The scheme was then adjusted roughly to be consistent in terms of lightness and overall contrast.