In Sublime the vertical lines showing matching indents are a great help, and it is wisely Tufte-esque that they are faint but visible. But even better would be for the colours to rotate between three possibilities: 0 mod 3 ⟹︎ the current pale grey; 1 mod 3 ⟹︎ faint medium-lightness blue; 2 mod 3 ⟹︎ faint red.
Similar was requested in December 2014, so 8¾ years ago. That suggested a tri-alternation grey green red, but this has changed the request green➝︎blue ∵ colour-blindness concerns.