There is an ergonomically correct color scheme called "Solarized" that you can read about here: https://ethanschoonover.com/solarized/
I would add the theme, but I feel it would be better if RJ did this, but you decide.
Suggestion for a new theme
Re: Suggestion for a new theme
You can prepare it yourself and send to Rickard, and he would add it in the next version, you know

Alium tibi quaere fratrem; hic, quem tuum putas, meus est. Titus Flāvius Caesar Vespasiānus Augustus
Re: Suggestion for a new theme
Well I'm not going to do that. For one thing, in my opinion, the Solarize color scheme isn't all that great like it theoretically was supposed to be. If you are in a dark room and with no other light-themed apps in the background open, that's the only time it is readable, otherwise it easily gets washed up (loses contrast) by the ambient background/light. I substituted my own (slightly brighter and more contrasty) colors loosely based on the Solaris template and that's good enough for now.You can prepare it yourself...
The other thing is, I don't know how to do themes, nor do I want to know because I'm not interested in becoming an expert on RJTextEd (or any other text editor for that matter). I just want something that works and is easy to modify so I can concentrate on what I do want to be an expert on.
But I did find a bug or two as usual:
The Selected color textbox in Environment➜Themes➜Customize...➜Select Color only doesn't work on my Win7 Home x64 OS using RJTextEd version 14.51 (64-bit), unless I enter the new color in the Selected color textbox and hit <enter>, and then OK.
Speaking of which, I can't get the alpha slider to work at all. In fact, I can't manually enter the alpha in the Selected Color textbox and have it work. It appears to work but when click on OK and then Apply, nothing changes. When I reopen the Select Color dialog, the alpha slider is back to the default position it was in originally and the extra digits I added in the Selected Color textbox have disappeared.