Add Lambda Core in native HTML and CSS

.github/workflows/test.yml

@@ -11,13 +11,14 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      # Python, Node.js, Perl, GCC/G++ 14, and the .NET SDK (F#) come
-      # preinstalled on the runner.
+      # Python, Node.js, Perl, GCC/G++ 14, the .NET SDK (F#), and Google
+      # Chrome come preinstalled on the runner. poppler-utils supplies
+      # pdftotext, which observes the HTML+CSS implementation's rendering.
       - name: Install toolchains not preinstalled on the runner
         run: |
           sudo apt-get update
           sudo apt-get install -y --no-install-recommends \
-            racket ruby lua5.4 ghc ocaml elixir
+            racket ruby lua5.4 ghc ocaml elixir poppler-utils
 
       # Clojure's deps.edn CLI (clj) is not in apt; use the official installer.
       - name: Install Clojure CLI

ROADMAP.md

@@ -45,6 +45,16 @@ Folders without a `test.sh` are skipped until backfilled.
       test.sh + expected-output.txt in new-language PRs, and enable branch
       protection so PRs need a green check to merge.
 
+## Milestone 1.5 — native browser experiment
+
+- [x] **Step 1 — HTML + CSS, with no JavaScript.** A self-contained HTML
+      document that encodes Church-boolean selection trees and observes Church
+      numeral application through CSS counters. Use no JavaScript, SVG,
+      external resources, or non-native browser extensions. Render it in a real
+      browser for the regression test and capture the baseline only from that
+      observed rendering. Verified in headless Google Chrome; the root harness
+      reports `PASS h/html-css`.
+
 ## Milestone 2 — fill out the missing major languages
 
 One language per step, each landing as its own PR with implementation, README,