Is there a simple way to display a color bitmap in grayscale with just HTML/CSS?

It doesn’t need to be IE-compatible (and I imagine it won’t be) — if it works in FF3 and/or Sf3, that’s good enough for me.

I know I can do it with both SVG and Canvas, but that seems like a lot of work right now.

Is there a truly lazy person’s way to do this?

jjjjj