How can I use 3-digit color codes rather than 6-digit color codes in CSS?

Question

I recently went through my CSS file and switched all my six-digit hexadecimal codes to simple three-digit codes (for example, my #FDFEFF got shortened to

Answer 1

That is true, but this transformation is not general:

#FFF == #FFFFFF
#CCC == #CCCCCC

So it "doubles" each hexadecimal digit. So it is not the same color. It is however possible that it looks the same because the differences are minute. A calibrated color workflow could help in this case.