Read through the HTML5 spec if you want to do anything frontend related. Yes, it can be boring at times, but using a TTS extension for your browser helps a lot.

It’ll teach you which HTML5 tags exist, which attributes exist for each tag, which tag goes within which tag, etc. Very helpful if you want to actually learn an up-to-date HTML5.

It will provide a very good fundamental knowledge before you start learning whatever popular JS framework exists in a few years.