I love the new darkmode however I have an issue with colors. I have 'Auto color based on nickname' selected in the address book -> colors tab. This works as expected however some of the darker colors, like dark blue, dark purple, dark red are near impossible to read in darkmode. I have even had some nicknames colored the same as the background. There is a formula to calculate the color contrast ratio that could be used to skip a color if there is not enough contrast. Search "what is the 4.5:1 rule" in your favorite search engine for more information. This 4.5:1 does refer to accessibility however it's relevant in this scenario also.
(I do hope I've posted this in the correct forum, it's not really a bug or is it?)