It is 9+ years later and we are still cleaning up after the damage the Document Outline Algorithm caused, which never existed, nor will it ever exist. https://developer.mozilla.org/en-US/blog/h1-element-styles/
Default styles for h1 elements are changing | MDN Blog

Browsers are starting to roll out changes in default UA styles for nested section headings. This post describes the incoming changes, how to identify if it's an issue on your websites, and hints for conformant and better-structured pages.

MDN Web Docs
@eric also "love" the whole "if you're using h1 inside a section, lighthouse/devtools will now warn you that you should also change the font-size yourself" ... you still don't get it, muppets? it's not just the visual size that matters, but the actual heading level as exposed to assistive technologies... fucking sigh...

@patrick_h_lauke
Yeah, embedding this as a quote on my 2016 piece (and maybe my 2013 piece) about this bullshit.

@eric