Hello! I’ve been using Wanikani for some time now and was wondering if anyone else felt the same way about this.
I find the pink they use when teaching vocabulary to be really bright and I find my eyes to fatigue really fast because of it. I know there are other ways to inject css to make it darker, but having some way for this to be done natively instead (such as a dim-mode) would be really nice 
I believe there are a couple of user scripts that provide different colour schemes and/or allow some customization. Breeze Dark 2 is one of them if I recall correctly.
This might be what you are looking for
Sometimes I just change my displays setting to monochrome if my eyes are really tired. But I rarely do it.
This website also gives you more options. But I have never tried any from it. Use it at your own judgment.
I know this exists, but it would be nice to have something natively built-in instead of having to use css-injection (which is what my original post says). Even a colour-blind mode to make pinks less vibrant would be nice. Plugins that solve this cause slow-down in my browser.