For my eyes black on white is far superior. White on black results in haloing around all text, whereas black on white results in generally pretty crisp text. This is why I use light themes and high-contrast mode for anything that supports it. (The glaring exception is Spotify)

The basic idea is that for folks with blurred vision (not out of focus, literally blurred), bright colors will erode into dark surroundings. Dark text on light background means the text is uniformly slightly lighter than "ground truth", light text on dark background means a distracting halo forms around the text.

This. A thousand times. I'm an oldster -- and no, 40 is not old. My vision varies from dead sharp to blurry depending on eye fatigue, probably blood sugar levels, and how my rather large floaters are behaving. But by the end of a day of reading, it's almost guaranteed that my eyes will be blurry from fatigue and age-related stiffness, complicated by that modern-day miracle -- replacement lenses for cataracts. As a consequence, reading any light text on dark background when my eyes are blurry is just a mess of haloing. The haloing bleeds three or four lines above and below the line I am reading, creating a big fuzzy mess that's annoying and hard to read.

To be clear when I mention floaters, I don't mean the little black squigglies that everyone experiences at any age. Rather mine are more like floating but not completely un-anchored translucent blurs that move right when my eyes move left. I suspect mine are Weiss rings.

Know that all that time you spent choosing a font color that is one-level of gray removed from invisible ink will never be enjoyed by me. I've overridden the the default font and font color in my browser to be a nice large, heavy, mono-spaced black font. When my eyes are fresh, yeah, I can read your 300-weight pseudo-invisible ink just fine, but it flatly irritates me, hence the overrides. And right click inspect is my boon companion when reading any page too-trendily designed.

If you're less than 40, it's hard to appreciate how age changes one's eyes. So if you're a youngster, have a bit of sympathy for us old folks when choosing color schemes. Or don't. I'm happy you can do creative, and that those of us with less-than-youthful vision can make adjustments. Best of both worlds.

This is great insight, thank you for commenting. I'm very much interested in design that is at the intersection of accessible and beautiful at the same time. Unfortunately those things seem to be pretty mutually exclusive but it's my belief they don't have to be.

I always appreciate this sort of feedback - especially as a young guy! :)

huh - oddly enough I have the opposite (over 50, near sighted, blood sugar issues)...

but I find 'warm' colors with medium contrast on black to be easiest to work with (yellow, amber, green, etc.).

I tend to work a lot at night/fairly dim rooms though, not sure if that makes a difference.

Sounds like you have astigmatism. It can be mostly corrected by glasses.

But yes a dark on light theme helps a lot too! I like that almost all apps support light and dark modes these days so I can just switch to what I feel like. I have some astigmatism to but not very bad and I like the calm of a dark screen at night.

Not astigmatism. But the true reason makes me seem dumb as shit so I wont get into that. :)

The halo coming from your own vision, not as an artifact of the LCD screen or something like that, right?

Thanks for the information, this is interesting to note!

Not the GP, but yes, it's a perceptual effect from one's own vision.

There are a number of aspects to light mode vs. dark mode. One important aspect is ambient lighting: to avoid eye strain, the average display brightness should be similar to the ambient lighting level. At least that's the general recommendation, and it matches my experience. So unless one works in the dark, that means light mode is more ergonomic. At night in bed though I read with dark mode on an iPad.

There also seems to be some scientific evidence that dark on light text is generally easier on the eyes than light on dark text: https://graphicdesign.stackexchange.com/a/15152. I don't know how well-grounded that is (and whether it's independent from ambient lighting), but from personal experience I tend to agree with it. With white text on black, there is some blooming effect that makes reading more straining.

Finally, there are still many GUI applications that do not support dark mode very well (if at all), and a mixed environment (e.g. a dark-mode web site on a light-mode desktop) is just unpleasant.

For all those reasons, black on white works better for me.

>>There also seems to be some scientific evidence that dark on light text is generally easier on the eyes than light on dark text: https://graphicdesign.stackexchange.com/a/15152.

I've seen this idea mentioned before, and while I don't know for 'average user' for my near sighted old butt, generally working in a fairly dark room... 'Dark themes' are much easier for me to work with for long periods.

I like 'medium' contrast (ambers, yellows, greys, greens) on a dark background the best.

> working in a fairly dark room

Ambient lighting levels certainly affect the equation.

Yeah - I just find it interesting that I've gravitated to preferring darker environments for screen work...I see those 'room setups' where people have bright sunny windows near the computer and just think "oh god, the glare!" :-P

> One important aspect is ambient lighting: to avoid eye strain, the average display brightness should be similar to the ambient lighting.

Which average (mode, median, arithmetic mean, geometric mean, harmonic mean, other?) of which measure of brightness?

> So unless one works in the dark, that means light mode is more ergonomic.

Does it? I’d like to see the work on that. IME, with common monitor settings, the brightness of most of the screen in light mode is typically much brighter than anything other thab directly looking straight at light fixtures in a typical work environment, it doesn't tend to approximate the ambient lighting level. Light mode on a purely reflective e-Ink type display would approximate ambient lighting, but that's not the kind of display usually used.

> With white text on black, there is some blooming effect that makes reading more straining.

This depends heavily on the display. White text on a black background is a joy to read on an OLED screen.