They're not really 'tricks' as much of mentions of assorted features of HTML and CSS. You get to discover a similar assortment of things (with much more immediately available detail and many examples) just clicking around MDN.
What's the difference?
That’s fair, "tricks" may be overselling it. The website is meant to be a small, opinionated collection of features I want to remember, not a replacement for an authoritative reference like MDN. I can probably make that positioning clearer.
Sure, they're not "tricks", but it's also definitely not the same as what you get randomly browsing formal documentation.