Stylesheet for printing, background-color ignored

I create a table where I cycle between giving each tr the class "odd" and "even". In my stylesheet I've got this:

 table tbody tr.odd {
     background-color: #cccccc;
 }
 

This works from the browser but not when printing. Everything else in my media stylesheet works except this background-color.

I have colors enabled for printing, I can print images with colors... so?

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