Reskin book with custom Tailwind Antora UI matching wincon

The Antora default UI had no design relationship to
wintermeyer-consulting.de (Roboto webfonts, generic blue/grey palette,
no dark mode). A reader clicking through from wincon to this book
landed in a site that looked unrelated.

Replace the default UI with a custom bundle in ui-bundle/ built on
Tailwind v4, authored to the same tokens as wincon: system fonts only
(system-ui / Georgia / ui-monospace), neutral-50/#0e0e0e backgrounds,
neutral-900/#f0ede6 text, lime-700/#c8f55a accent. Dark mode via
prefers-color-scheme with no toggle. Chrome mirrors wincon's top_nav
and four-column footer.

Structural changes beyond the CSS:

- New ui-bundle/ keeps Antora's handlebars plumbing (helpers, layouts,
  nav-menu, site.js) so sidebar toggle, copy-code button, and link
  resolution keep working. Only header-content.hbs and
  footer-content.hbs are rewritten for wincon chrome.
- antora.yml `version: ~` so URLs drop the /main/ segment; the book
  now lives at /book/index.html, /book/phoenix/index.html, etc.
- Playbooks now point at the local bundle zip; supplemental-ui/ is
  removed (superseded by the bundle).
- .tool-versions bumped to nodejs 20.19.0 for Tailwind v4.

Content-area restyle under .doc covers all AsciiDoc output:
admonitions (NOTE/TIP/WARNING/CAUTION/IMPORTANT) with attr(title)
labels, code blocks on #131313, tables, callout pills with the
<b>(N)</b> text fallback suppressed, inline-code overflow-wrap to
prevent mobile overflow. The sticky breadcrumb band tried earlier is
gone in favour of a small serif-italic "← <book title>" kicker above
each h1 — harmonises with wincon's Georgia wordmark instead of
clashing with a mono uppercase row. Edit-this-page moved to a muted
footer row at the end of each article.

CI and deploy path are intentionally unchanged in this commit; the
sub-path integration into wincon comes in a follow-up.

Author: wintermeyer

.tool-versions

@@ -1,3 +1,3 @@
 elixir 1.18.3
 erlang 27.2.3
-nodejs 18.16.0
+nodejs 20.19.0

README.md

@@ -1,7 +1,54 @@
-# Phoenix Beginner's Guide
+# Elixir, Phoenix and Ash Beginner's Guide
 
-We use https://antora.org to convert the AsciiDoc to HTML.
+Content is authored in AsciiDoc under `modules/ROOT/pages/` and rendered
+by [Antora](https://antora.org). The visual style matches
+[wintermeyer-consulting.de](https://wintermeyer-consulting.de) and is
+produced by a custom Tailwind CSS v4 UI bundle that lives in
+`ui-bundle/`.
 
-Build the HTML with this command:
+## Build
 
-    npx antora antora-playbook.yml
+The site build is two steps: first build the UI bundle, then run Antora.
+
+```sh
+# 1. Build the UI bundle (produces ui-bundle/build/ui-bundle.zip)
+cd ui-bundle
+npm install
+npm run build
+cd ..
+
+# 2. Render the site against the local source (build/site/)
+npx antora --fetch antora-local-playbook.yml
+```
+
+Open `build/site/index.html` in a browser to preview.
+
+To render the production playbook (pulls content from the remote repo
+instead of the working directory), swap step 2 for:
+
+```sh
+npx antora --fetch antora-playbook.yml
+```
+
+## UI bundle development
+
+Work on the chrome and styles lives in `ui-bundle/src/`:
+
+- `css/site.css` — Tailwind v4 source (`@theme` tokens, `@custom-variant
+  dark`, and `@apply`-scoped rules for Antora's class surface)
+- `partials/header-content.hbs`, `partials/footer-content.hbs` — the
+  wincon-matching top nav and four-column footer
+- `partials/*.hbs`, `layouts/*.hbs`, `helpers/*.js`, `js/site.js`,
+  `img/*.svg` — carried from the Antora default UI so Antora's internal
+  plumbing and sidebar JS keep working
+
+For a tight iteration loop:
+
+```sh
+cd ui-bundle
+npm run dev      # Tailwind CLI in watch mode
+# then, in another shell, rebuild the bundle + site on demand
+npm run build && cd .. && npx antora --fetch antora-local-playbook.yml
+```
+
+Dark mode follows the OS `prefers-color-scheme`; there is no toggle.

antora-local-playbook.yml

@@ -12,9 +12,8 @@ content:
 
 ui:
   bundle:
-    url: https://gitlab.com/antora/antora-ui-default/-/jobs/artifacts/master/raw/build/ui-bundle.zip?job=bundle-stable
+    url: ./ui-bundle/build/ui-bundle.zip
     snapshot: true
   output_dir: antora-assets
-  supplemental_files: ./supplemental-ui
 runtime:
   fetch: true

antora-playbook.yml

@@ -11,9 +11,8 @@ content:
 
 ui:
   bundle:
-    url: https://gitlab.com/antora/antora-ui-default/-/jobs/artifacts/master/raw/build/ui-bundle.zip?job=bundle-stable
+    url: ./ui-bundle/build/ui-bundle.zip
     snapshot: true
   output_dir: antora-assets
-  supplemental_files: ./supplemental-ui
 runtime:
   fetch: true

antora.yml

@@ -1,6 +1,6 @@
 name: book
 title: An Elixir, Phoenix and Ash Beginner's Guide
-version: main
+version: ~
 start_page: ROOT:index.adoc
 nav:
 - modules/ROOT/nav.adoc