I love it that people have an alternative solution to every simple request here but, no, I don't want to install another FF plugin just to have a different style here. It'd take about a minute to add a style with a darker background and more people than just me would benefit from it, so it's not really much of a request. We've all got our own colour preferences and I hope it's common knowledge enough that many find reading black on pure white on a monitor hard on the eyes. If you don't, good for you. Some of us are not so lucky.