How much HTML, CSS, & JavaScript is enough?
Do You Need That Much HTML/CSS To Be A Developer?
It would be best if you learned CSS while you learn HTML: it is a critical part of web pages and anyone who says it should be remembered after everything else is sending you down the (wrong) path of mixing content and presentation.
Javascript is often used to manipulate the page, so a critical part of that is understanding how the styles influence the display of a web page.