ui glitch: separator lines have different colors

there is a small visual oddity:
the separator line between "mode selector" and "sidebar" has a different color than the separator line between "sidebar" and "editor". screenshot attached (it's a one-pixel separator, so one needs to look quite precisely, consider resizing the image when viewing)

also, not sure if it is intended, but he vertical separators also intersect with the horizontal separator between menu bar and toolbar