Mostly, I use Chrome as my browser, but reading this site on it was causing a great deal of eyestrain. I tried using Firefox and MS Edge and found significant improvements over Chrome. Both made the default grey just enough darker to be more readable, and the line spacing did not seem as spread out. MS Edge had a slight edge (sorry) over Firefox because there seemed to be a bit less superfluous white space in the body of the text.
One other modification I made in all 3 browsers was that I un-maximized the browser window and made it much narrower. This eliminated almost all of the excess white space on the left and right margins. It’s as if DK5 is meant to be read in portrait rather than landscape orientation. I suppose this was done to facilitate reading on mobile devices and tablets.
I would still prefer that the text be a shade darker grey, but the changes I made will allow me to keep reading DK without getting a headache.