Badge fixes and badge docs

Switch some conformance/validation icons from blue to yellow. Update the
W3C icon to the latest official ones in
<https://www.w3.org/WAI/standards-guidelines/wcag/conformance-logos/>
and <https://www.w3.org/QA/Tools/Icons>.

content/meta/badges.md

@@ -31,18 +31,16 @@ Read more about the design of this site in my [site design standards page]({{<re
 {{<picture name="b/is_it_slow_say_so" alt="Is it slow? Say so!" width="162" height="62" class="pix">}}
 {{<picture name="b/dark-mode" alt="Made for Dark Mode!" width="162" height="62" class="pix">}}
 <a href="https://git.sr.ht/~seirdy/seirdy.one/tree/master/item/linter-configs/vnu_filter.jq">{{<picture name="b/html5" alt="W3C valid HTML5." width="162" height="62" class="pix">}}</a>
-<a href="https://git.sr.ht/~seirdy/seirdy.one/tree/master/item/linter-configs/vnu_filter.jq">{{<picture name="b/vcss" alt="W3C valid CSS." width="162" height="62" class="pix">}}</a>
+<a href="https://git.sr.ht/~seirdy/seirdy.one/tree/master/item/linter-configs/vnu_filter.jq">{{<picture name="b/valid-css" alt="W3C valid CSS." width="162" height="62" class="pix">}}</a>
 <a href="https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Fseirdy.one%2Fatom.xml">{{<picture name="b/valid-atom" alt="Valid Atom feed." width="162" height="62" class="pix">}}</a>
 <a href="https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Fseirdy.one%2Findex.xml">{{<picture name="b/valid-rss" alt="Valid RSS feed." width="162" height="62" class="pix">}}</a>
-<a href="https://www.w3.org/TR/WCAG22/">{{<picture name="b/valid-wai-aaa" alt="W3C WAI-AAA WCAG 2.0." width="162" height="62" class="pix">}}</a>
+<a href="{{<relref "/meta/wcag-conformance.md">}}">{{<picture name="b/wcag22" alt="W3C WAI-AA WCAG 2.2." width="162" height="62" class="pix">}}</a>
 <a href="https://indieweb.org/Webmention">{{<picture name="b/webmentions" alt="Webmentions supported." width="162" height="62" class="pix">}}</a>
 <a href="https://internet.nl/faqs/ipv6/">{{<picture name="b/ipv6" alt="The word “IPv6” next to a green checkmark." width="162" height="62" class="pix">}}</a>
 
 ### Notes on "About this site" badges
 
-The W3C Valid HTML5 badge isn't offered by the new Nu HTML Validator, but I use it anyways because my markup is valid. I regularly test all 200-something pages on this site with a local instance of the validator.
+The W3C Valid HTML5 badge isn't offered by the new Nu HTML Checker because [HTML5 is about conformance, not validity](https://html5doctor.com/html5-check-it-before-you-wreck-it-with-miketm-smith/). I use it anyways because my markup does fully conform _and_ is well-formed polygot XHTML5, despite false-positives from validators; [see my conformance statement]({{<relref "/meta/site-design.md#conformance">}}).
-
-Before you email me about how my site has invalid markup and doesn't deserve the "Valid HTML5" badge: The validator also has false positives, which I report upstream (and sometimes fix) and silence in a JQ filter. I use a bleeding-edge version of the Nu HTML Checker and its Jigsaw CSS Validator dependency, as those have the fewest false positives.
 
 ## Ideological affinity, web-related
 

content/meta/site-design.md

@@ -11,8 +11,7 @@ This site may look bare-bones on the surface, but I put much thought into it. I
 
 {{<toc>}}
 
-Accessibility statement
+## Accessibility statement
------------------------
 
 I hold seirdy.one to the highest accessibility standards possible. For more information about seirdy.one's accessibility-related work, read {{<mention-work itemtype="BlogPosting">}}{{<cited-work url="https://seirdy.one/posts/2020/11/23/website-best-practices/" name="Best practices for inclusive textual websites" extraName="headline">}}{{</mention-work>}}.
 
@@ -74,16 +73,19 @@ WAVE reports no errors. AXE sometimes fails to measure contrast, but otherwise r
 
 I run axe-core, the IBM Equal Access Accessibility Checker, the Nu HTML Checker (local build, latest commit), and webhint on every page in my sitemap. After filtering out false-positives (and reporting them upstream), I receive no errors. I repeat this run with every change to my Hugo templates and stylesheets.
 
-To work around [issue 1008 in IBM Equal Access Checker](https://github.com/IBMa/equal-access/issues/1008), I remove all instances of `content-visibility` from my site's CSS before running `achecker` from the command line.
+<del datetime="2024-04-22">To work around [issue 1008 in IBM Equal Access Checker](https://github.com/IBMa/equal-access/issues/1008), I remove all instances of `content-visibility` from my site's CSS before running `achecker` from the command line</del>. <ins datetime="2024-04-22">Update: the issue has been resolved</ins>
 
-Compatibility statement
+## Compatibility statement
------------------------
+
+### Conformance
 
 This website uses well structured, semantic, [polygot XHTML5](https://www.w3.org/TR/html-polyglot/) (including [WAI-ARIA](https://www.w3.org/WAI/standards-guidelines/aria/) and [DPUB-ARIA](https://www.w3.org/TR/dpub-aria-1.1/) extensions where appropriate), enhanced with CSS for styling.
 
-This website does **not** rely on modern development practices such as CSS Grid, Flexbox, SVG 2, Web fonts, and JavaScript; this improves support in older browsers such as Internet Explorer 11. Users can access this site without extra plug-ins or polyfills. The site does use strictly-optional modern features (e.g. CSS containment) that don't create significant visual differences.
+This website conforms to Web standards. Each build runs `xmllint` to catch syntax errors. Every few commits, I run a local build of [the Nu HTML Checker](https://github.com/validator/validator) and [html proofer](https://github.com/gjtorikian/html-proofer) across all 200-something pages in my sitemap, and see no errors. I do [filter out false Nu positives](https://git.sr.ht/~seirdy/seirdy.one/tree/master/item/linter-configs/vnu_filter.jq), and I [report and fix false-positives](https://github.com/w3c/css-validator/issues?q=author%3ASeirdy) when possible.
 
-This website conforms to Web standards. Each build runs `xmllint` to catch syntax errors. Every few commits, I run a local build of [the Nu HTML Checker](https://github.com/validator/validator) and [html proofer](https://github.com/gjtorikian/html-proofer), and see no errors. I do [filter out false Nu positives](https://git.sr.ht/~seirdy/seirdy.one/tree/master/item/linter-configs/vnu_filter.jq), and I [report and fix false-positives](https://github.com/w3c/css-validator/issues?q=author%3ASeirdy) when possible.
+### Cross-browser compatibility
+
+This website does **not** rely on modern development practices such as CSS Grid, Flexbox, SVG 2, Web fonts, and JavaScript; this improves support in older browsers such as Internet Explorer 11. Users can access this site without extra plug-ins or polyfills. The site does use strictly-optional modern features (e.g. CSS containment) that don't create significant visual differences.
 
 I also perform cross-browser testing for HTML [and XHTML versions](#markup) of my pages. I test with, but [do not necessarily endorse]({{<relref "/notes/pale-moon.md">}}), a large variety of browsers:
 
@@ -122,8 +124,7 @@ Some engines I have not yet tested, but hope to try in the future:
 - [Moon](https://github.com/ZeroX-DG/moon)
 - [hastur](https://github.com/robinlinden/hastur)
 
-Machine-friendliness
+## Machine-friendliness
---------------------
 
 I use machine-friendliness as an alternative perspective to traditional search-engine-optimization, the latter of which incentivizes low-quality content. It's a major part of what I've dubbed ["agent optimization"]({{<relref "notes/agent-optimization.md">}}).
 
@@ -157,8 +158,7 @@ This site works well in the Diffbot article extractor. Diffbot powers a variety
 
 This site has poor compatibility with the Chromium DOM Distiller's flawed techniques. Regions with high link-densities, such as citations, get filtered out. DOM Distiller also removes footnotes, and sometimes [DPUB-ARIA](https://w3c.github.io/dpub-aria/) sections near the end of an article (acknowledgements, conclusions).
 
-Static IndieWeb
+## Static IndieWeb
----------------
 
 I want to show how far I can take IndieWeb concepts on a fully static site, leaving dynamism to ancillary services.
 
@@ -219,8 +219,7 @@ I'm not opposed to these features, but I probably won't implement support for th
 
 - Some sort of daemon to replace the Bridgy service. I don't plan to run my own Bridgy instance: Bridgy requires Python, but I prefer installing statically-linked native executables.
 
-Privacy
+## Privacy
--------
 
 This site is **privacy-respecting.** Its <abbr title="Content Security Policy">CSP</abbr> blocks all scripts, third-parties, and other problematic features. For details on this site's privacy, [read the privacy policy](../privacy/).