In the source you'll find every occurence of pi as <span style='font-family:Symbol'>p</span> Apparently the Symbol typeface has π as p: https://en.wikiped

In the source you'll find every occurence of pi as <span style='font-family:Symbol'>p</span> Apparently the Symbol typeface has π as p: https://en.wikipedia.org/wiki/Symbol_(typeface)#Encoding https://en.wikipedia.org/wiki/Symbol_(typeface)#Encoding. I guess that ones who has the correct font installed will see the expected character.