Technically, this is not advised in the Tango guidelines. To ensure correct contrast on a wide range of backgrounds, there needs to be an outline whose color is specified as "the primary color at 20% lightness value".pablogil wrote:I have lowered the color contrast for "unselected" axis by making edges color equal to shape color
There is some room to interpret 'primary color' but the guidelines (for good reason) cite the dark outline as a requirement (though the highlight is just advised for most materials but optional)
I agree that your white outline solves the same problem, but would inverse the order suggested by the Tango guidelines - and requires an extra pixel anyway so comes to the same trade-off.
If you want to play around with it (and still respect Tango), try choosing different fills for the axis from the Tango palette, then in the stroke simply set the Lightness value to 20% of the fill Lightness.
(See the colors in the selection box in this image for an example, the main color is Chameleon 2, the highlight stroke is Chameleon 1 and for the outer stroke I simply set the stroke to Chameleon 2 then divided the L (116) value by 5 rounded to nearest (23)).
Works with any color and gives consistently excellent results!
I can write up a tutorial on my wiki talk page if you like? You can play with all the color combinations you like.
Alternatively, maybe the axis could be a black glassy material? Then you could use a dark base color with dark outline and only a single 2px stroke of high contrast highlight?
e.g. :