When starting a plain HTML page without a framework and you are going to activate the Design panel, the theme.css file added to the page will include the normalization css code.
For those like me who didn’t read the instructions, if you are wondering why you can’t find fonts in the font selector for styling, activate the Design panel and you will find the fonts there that you want to add to the theme.
If you are doing a Tailwind interactive tutorial, and your page doesn’t look styled, again, activate the Design panel.