Printing renders light grey as black

I have a weird printing problem which I'm hoping someone can help me with.

If I print the generated PDF from Chrome or Internet Explorer it renders light grey blocks as black. This happens in Internet Explorer and Chrome, but not Adobe. Interestingly the preview looks ok it is only the actual print that comes out wrong.

Any advice greatly appreciated.

https://db.tt/uYm0iuVD includes the Source HTML, the PDF and a photo of the offending print. It's been tested on multiple printers.

Hello,

I tried to print the PDF in Chrome (Linux) on an HP LaserJet printer and it came out correctly: see here

Your problem may be caused by this bug:
https://code.google.com/p/chromium/issues/detail?id=226137

So after reading the bug I changed:

background-color: rgba(0, 0, 0, 0.05);

to:

background-color: #f2f2f2;

and it now prints fine, thanks :)