いつ、どう、どれ、どこ、だれ、なに、etc. are all question words.
However, いつでも、どうでも、どれでも、どこでも、だれでも、なんでも、etc, all mean 'Any ___'.
What's making this happen? Is it just a special exception that evolved over time, or is there some reason for this considerable shift in meaning?
I ask as while I'm still not 100% when it comes to the particles で、も、and でも, I still don't get what's going on here.