Why is the web compiler always ignoring CSS being put inside HTML?

Question

Example: https://code.sololearn.com/WL6PcVsXX6w6/#html

Answer 1

Yes it is ur mistake.
U can't style like tht

Answer 2

Corrected
https://code.sololearn.com/Wuqo5587E602/?ref=app

Answer 3

VS code does not ignore this. It's not my mistake here.