theme
Prefer a theme not a bright as light and not dark. Contrast is the element missing in the new dark theme and light theme's text and icons. I know the main concern is legibility, so enough visual definition gives the brain an easy job of "seeing".
Maybe use a slightly darker blue in some parts of the light theme?
Maybe a charcoal grey that is lighter than the new dark theme?
Maybe in adjusting those colors take care to not lose the clarity of the icons and other symbols?
Maybe contrast is not the right word. Pose the question, "How much effort does my eye and mind use to see and stay on the page?
Some months back or in late 2015, you gave the pages an excellent update that addressed similar concerns.