[Mapcss] Styles that work with and without background?

[Steve Bennett]

Hi all,
  One issue I'm having with making styles for Potlatch2 is coming up
with styles that work well over a background and without one. Just
wondering if anyone has any tips?

For example, I made a style for "highway=service; service=alley" which
was a white dashed line with grey between the dashes. It looked fairly
good over the aerial photography background (the white stands out well
against the grey and dark colours of streets, houses etc). But on a
plain white background, all you see are the tiny grey dots.

Any advice?

Steve