She does mention that the first commit was already of a partially finished version:

> Sadly the project began on my desktop, so my first git commits were of an already-in-progress drawing.

from https://github.com/cyanharlow/purecss-francine/issues/13#iss.... So, the actual amount of time taken is likely to be much longer.

Also very worth checking out the timelapse gif posted there: https://imgur.com/K2xLX3g