Answer prose round 1: 0 🔴, 7 🟡 (0 misread); the header opens with what it checks, README says what fails even guarded and how a plugin is checked, the changelog stops claiming a floor change

CHANGELOG.md

@@ -8,10 +8,10 @@ at boot. Entries start at 0.3.0.
 
 ### The tests fail on a stylesheet feature the browser floor lacks
 
-Every stylesheet in the repo, the examples' included, is checked against Chromium 87, Safari 15 and
-Firefox 115 using MDN's compat data; a feature one of them lacks passes only inside an `@supports`
-that names it. The core stylesheets now guard each such feature, which those engines skip instead
-of misreading. Pages render as before in current browsers.
+`npm test` checks every stylesheet in `public/`, `examples/` and `plugins/` against Chromium 87,
+Safari 15 and Firefox 115: a feature one of them lacks fails it unless an `@supports` around it
+names that feature. Mount a plugin in `plugins/<id>/` to check its stylesheets. Pages render as
+before in every browser.
 
 ### Every release reaches Docker Hub, and the Hub page has a short description
 

README.md

@@ -1059,11 +1059,12 @@ Chromium 87, Safari 15 and Firefox 115, the engines in years-old TVs, kiosks and
 features [Baseline Widely available](https://web-platform-dx.github.io/baseline/) (in every
 major engine for 30 months) may shape how a page looks; anything newer, like popovers or anchor
 positioning, only enhances. A feature the floor engines lack, such as `:has()`, may
-decorate a page but never decide whether something shows or can be read. The tests hold every
-stylesheet in `public/` and `examples/` to this floor, against MDN's compat data: a feature a floor
-engine lacks fails them unless it sits inside an `@supports` whose condition names it
-(`src/ui/stylesheet-floor.ts` lists what it checks). A plugin stylesheet mounted from outside the
-repo is not checked.
+decorate a page but never decide whether something shows or can be read. `npm test` fails on a
+stylesheet using a feature Chromium 87, Safari 15 or Firefox 115 lacks, unless an `@supports`
+around it names that feature. It checks every stylesheet in `public/`, `examples/` and `plugins/`,
+so mount your plugin in `plugins/<id>/` and run it. A few constructs fail even when guarded, such as
+`@layer`, nested rules and media range syntax, while a media feature passes unguarded, since a
+browser without it skips the query; `src/ui/stylesheet-floor.ts` lists the rules.
 
 **A field whose options depend on another field is asked for in steps, one GET form each**, so every
 choice is in the URL, and nothing typed is lost to one because nothing is typed until they are made.