Using an eink screen as almost my primary monitor for a few months has firstly made all the difference to my eyestrain — I can actually read for more than 10 minutes at a time now, and very likely won't have a headache by the end of the day — but has also made me see UI design in a completely different way. Dark themes don't work well on eink, but I can't really criticise designers for that; what I can say though is that many pages simply don't have adequate contrast, regardless of their colour scheme.