Light text on a dark background is becoming increasingly fashionable, especially since many computer and mobile operating systems started offering a ‘dark mode’ as an option. Research however shows that it’s not great for comprehension, and it should be avoided on our websites and longer email communications.
In the 2020 article Dark Mode vs. Light Mode: Which Is Better? from respected user experience consultancy NN/g, the summary was: “In people with normal vision (or corrected-to-normal vision), visual performance tends to be better with light mode, whereas some people with cataract and related disorders may perform better with dark mode.”
What’s the science behind white text on black background not being as good? With a predominantly black screen, the iris needs to open up more to get light, and this results in the white letters apparently bleeding into their black backgrounds (called the halation effect). So in normal light conditions, ‘dark modes’ can put more strain on your eyes. I assume that the types of websites we manage are more likely to be looked at in an everyday office, rather than under a duvet, so we should always opt for black text on a white background if possible.
Do follow the links above for a lot more on the subject.