Viewport border width

The border of the viewport window is 4 pixels wide, which is too bold for me.
It stands out more because my background colors are dark.
I found that in in appearance-> colors I can change window border to a dark color to match my background, So I can make it actually appear like it is 2 pixels wide, but it still stands out too match. could you possible see you can give us option to change its color without effecting the value of window color 1 ?

Hi Yianni- added to the heap, thanks.