These 2 colors are too close and break functionality when used to identify the current tab
With the theme "City", colors @bg and @base2 are very close.
Their hex values are :
;; @bg: #1D252C
;; @base2: #20282F
In Gnomon, they are used for the background of tabs, and the background of the active (or hovered) tab. The user can not see the difference between these 2 very close colors, and can not see which tab is active (or hovered).
Suggested fix: assign another value @base2, that does not collide with any other value of the theme.