[mryall]

> As a reader, I don't want page authors to start hard coding sizes into these elements …

They mean h1 elements without a font-size specified in CSS (or style attribute) will be flagged as a warning. User agent styles can still override site styles if you want to set one.

> if I take some existing markup and blockquote it in some container, I'd expect the headings to shrink as they're now all sub-elements of some other section.

This logic only applied to the h1 element specifically, as it was an attempt to shoehorn some “clever” logic from the abandoned <h> tag proposed in a early draft of HTML5 (which was going to work the way you’d describe for headings at any level), on to the existing h1 element.

(Source: I used to follow the WHAT-WG mailing list closely during the HTML5 spec development process.)

[kevin_thibedeau]

These shouldn't be a warning. We're supposed to have graceful degradation without any requirement for CSS anywhere. Now the only "correct" way is a slew of media queries to set some designer's idea of the font for every possible viewport size. That is not how HTML is supposed to be rendered.

[mhnthrow]

> Now the only "correct" way is a slew of media queries to set some designer's idea of the font for every possible viewport size.

Nested H1s was never semantically correct in the first place, at least for accessibility purposes.

You can do flexible sizes without media queries (eg, viewport size units + clamp). Designers generally understand the web pretty well these days.

I only see one situation where people might have depended on these styles, but it's a big one - anywhere that you output the plain HTML of a "rich text" component from a CMS or whatever. There, if the stakes are low, it might not have been a big deal to just let the browser do it and headings might look too big sometimes now.

[mykhamill]

A warning IS graceful degradation, an error or unexpected behaviour would be ungraceful. The channel that warnings come over is separate from the channel the content is being rendered in and it shows, for those that look at it, that the system is degraded and an action would need to be done to restore it to a non-degraded state.

[marcosdumay]

The GP didn't find the right words.

This is not about graceful degradation. An HTML document without any CSS should never be in a degraded state. It should be perfectly usable and perfectly well accepted.

[zzo38computer]

I agree; a HTML document without CSS should be perfectly usable and OK (and ideally CSS should never be required; if CSS is disabled it ought to still work OK, too).

However, if CSS specifies some things and omits others that are related to it (one example is specifying the font size for one heading level but not another one; another example is specifying the background colour without specifying the foreground colour or vice-versa), then it makes sense to be a warning.

[joquarky]

I've been a pro web dev since 1995.

I can't articulate it and I could very well be on the wrong vibe, but this feels like the bad practice of relying on the failure mode within a try/catch for normal functioning.