A few things in it that I would not put into a beginner's (or any) guide:<p>- Semantic tags (header, footer, main, section): machine-readable semantics can be fun to play with if one is so inclined, one can go even for RDFa, but AFAICT they will not do anything visible or useful, especially for a small beginner's website, but they complicate the guide.<p>- CSS: the page itself uses low-contrast pink text on a pink background, which is hard to read (and goes against W3C accessibility guidelines, which can be checked with one of the online contrast checkers as well), and provides similar low-contrast examples. It also makes links bold on hover, which moves the texts that follow them, and which is annoying.<p>- Viewport meta tag: this can be controversial, I think, but the tag itself is rather a hack to tell a browser "this page is not too broken, it can be rendered with a legible font size without breaking the markup". Teaching beginners to repeat that feels wrong both as promotion of such bad browser behavior, and as a road to potential misuse even of that (and the next version of the guide will have to include a new "this page really is not broken" invocation).