Help me font-family css not working

Question

https://code.sololearn.com/WXW0KDtBbI8a/?ref=app

Answer 1

id="1", id="2" and id="3" are invalid id names for an element.id's must start with letters like id="a1",id="a2" e t.c

Answer 2

Or in other words, among other rules, IDs and classes can't start with numbers.

Answer 3

Thank you Brains ,Siddharth and ishola.