Keep the mobile nav reachable on engines without :has(), and fix the stylesheet header

CHANGELOG.md

@@ -6,6 +6,12 @@ at boot. Entries start at 0.3.0.
 
 ## Unreleased
 
+### The mobile nav stays reachable on engines without `:has()`
+
+At 860px and narrower, an engine without `:has()` (Chromium below 105, such as webOS TV 22 and 23)
+hid the sidebar off-canvas with no way to open it, so no page behind the nav could be reached. Now
+the sidebar moves off-canvas, behind the hamburger, only where `:has()` works. Elsewhere it stays in
+the flow above the content and the hamburger is hidden.
 ### The whole nav tree shows on engines without `:has()`
 
 On an engine without `:has()` (Chromium below 105, such as webOS TV 22 and 23, and Firefox below 121)

docs/reading-cost.md

@@ -30,3 +30,20 @@ Read most (opens and searches):
 - `AGENTS.md` 1
 - `src/ui/stylesheet-floor.test.ts` 1
 - `src/ui/theme-switch.test.ts` 1
+
+## Reading cost, chunk 3bf0b1a97d77, finished 2026-10-31T00:48:14Z
+
+167985 new input tokens before the first commit.
+
+Read most (opens and searches):
+
+- `public/css/styles.css` 17
+- `todo.md` 7
+- `README.md` 6
+- `public/css/auth.css` 5
+- `AGENTS.md` 1
+- `CHANGELOG.md` 1
+- `examples/plugins/scheduling/public/scheduling.css` 1
+- `examples/plugins/scheduling/views/overview.ejs` 1
+- `examples/plugins/scheduling/views/shifts.ejs` 1
+- `src/http/app.test.ts` 1

public/css/styles.css

@@ -2,8 +2,9 @@
    App Shell Template — pure HTML/CSS, no JavaScript
    -------------------------------------------------------------
    Architecture
-   - Design tokens via light-dark() so theme follows system by
+   - Design tokens are two raw palettes picked by a theme block, so
-     default and can be forced Light / Dark via radio + :has().
+     the theme follows the system by default and can be forced
+     Light / Dark via radio + :has().
    - Everything is a reusable "block": .nav-item, .filter,
      .chip, .badge, .btn, .menu, .table — combine freely.
    ============================================================= */
@@ -681,23 +682,28 @@ th[aria-sort="descending"] .sort-ico { transform: rotate(180deg); }
 /* ---------- 11. RESPONSIVE / HAMBURGER --------------------- */
 .scrim { display: none; }
 
+/* Off-canvas only where :has() works: without it nothing can read #nav-toggle, so the sidebar
+   stays in the flow above the content and the hamburger stays hidden. */
 @media (max-width: 860px) {
   .app { grid-template-columns: minmax(0, 1fr); }
-  .sidebar {
-    position: fixed; inset: 0 auto 0 0; width: min(86vw, var(--nav-w));
-    z-index: 60; transform: translateX(-100%);
-    box-shadow: 2px 0 24px rgba(0,0,0,.18);
-  }
   .content { grid-column: 1; }
-  .hamburger { display: inline-flex; }
-
-  /* checkbox-driven open state */
-  body:has(#nav-toggle:checked) .sidebar { transform: translateX(0); }
-  body:has(#nav-toggle:checked) .scrim {
-    display: block; position: fixed; inset: 0; z-index: 50;
-    background: rgba(0,0,0,.42);
-  }
   .search { min-width: 150px; flex: 1 1 auto; }
+
+  @supports selector(:has(a)) {
+    .sidebar {
+      position: fixed; inset: 0 auto 0 0; width: min(86vw, var(--nav-w));
+      z-index: 60; transform: translateX(-100%);
+      box-shadow: 2px 0 24px rgba(0,0,0,.18);
+    }
+    .hamburger { display: inline-flex; }
+
+    /* checkbox-driven open state */
+    body:has(#nav-toggle:checked) .sidebar { transform: translateX(0); }
+    body:has(#nav-toggle:checked) .scrim {
+      display: block; position: fixed; inset: 0; z-index: 50;
+      background: rgba(0,0,0,.42);
+    }
+  }
 }
 @media (max-width: 560px) {
   .crumbs, .page-sub { display: none; }

src/ui/stylesheet-floor.test.ts

@@ -16,6 +16,16 @@ for (const file of readdirSync(cssDir).filter((f) => f.endsWith(".css"))) {
 
 const stylesheet = readFileSync(join(cssDir, "styles.css"), "utf8").replace(/\/\*[\s\S]*?\*\//g, "");
 
+// The index of the `}` closing the block whose `{` is the first one at or after `start`.
+function blockEnd(start: number): number {
+  let depth = 0;
+  for (let i = stylesheet.indexOf("{", start); i < stylesheet.length; i++) {
+    if (stylesheet[i] === "{") depth++;
+    if (stylesheet[i] === "}" && --depth === 0) return i;
+  }
+  throw new Error("unbalanced braces in styles.css");
+}
+
 // The text is all there is to check: Playwright's engines all support `:has()`, so no E2E sees the
 // stylesheet an older engine gets.
 // Chromium below 105 and Firefox below 121 have no `:has()`, and nothing else reveals a folded
@@ -23,12 +33,7 @@ const stylesheet = readFileSync(join(cssDir, "styles.css"), "utf8").replace(/\/\
 test("styles.css folds .nav-children only inside @supports selector(:has(a))", () => {
   const open = stylesheet.indexOf("@supports selector(:has(a)) {");
   assert.ok(open >= 0, "no @supports selector(:has(a)) block");
-  let depth = 0;
+  const close = blockEnd(open);
-  let close = open;
-  for (; close < stylesheet.length; close++) {
-    if (stylesheet[close] === "{") depth++;
-    if (stylesheet[close] === "}" && --depth === 0) break;
-  }
   const outside = stylesheet.slice(0, open) + stylesheet.slice(close + 1);
   assert.ok(!/\.nav-children\s*\{[^}]*display:\s*none/.test(outside), "a .nav-children rule hides it outside the guard");
   assert.match(stylesheet.slice(open, close), /\.nav-children\s*\{\s*display:\s*none/, "the fold rule is gone");
@@ -44,3 +49,21 @@ test("styles.css hides the theme switch and the nav toggles where :has() is miss
   assert.match(block, /\.theme-switch\s*\{\s*display:\s*none/);
   assert.match(block, /\.nav-disc\s*\{\s*visibility:\s*hidden/);
 });
+
+// Without `:has()` nothing can check #nav-toggle, so an off-canvas sidebar there is unreachable
+// and the hamburger does nothing: the sidebar has to stay in the flow, with the hamburger hidden.
+test("styles.css moves the sidebar off-canvas at 860px only inside @supports selector(:has(a))", () => {
+  const open = stylesheet.indexOf("@media (max-width: 860px) {");
+  assert.ok(open >= 0, "no @media (max-width: 860px) block");
+  const close = blockEnd(open);
+  const media = stylesheet.slice(open, close);
+  const guard = media.indexOf("@supports selector(:has(a)) {");
+  assert.ok(guard >= 0, "no @supports selector(:has(a)) block inside the 860px media block");
+  const guardEnd = blockEnd(open + guard) - open;
+  const outside = media.slice(0, guard) + media.slice(guardEnd + 1);
+  const inside = media.slice(guard, guardEnd);
+  for (const offCanvas of [/translateX\(-100%\)/, /position:\s*fixed/, /#nav-toggle/, /\.hamburger/]) {
+    assert.doesNotMatch(outside, offCanvas, `${offCanvas} applies outside the guard`);
+    assert.match(inside, offCanvas, `${offCanvas} is gone from the guard`);
+  }
+});

todo.md

@@ -12,8 +12,6 @@
 
 | ID | Release | Blocked by | Exempt | Item | L | E | I | R | S | Moves | Score |
 |---|---|---|---|---|---|---|---|---|---|---|---|
-| 36 | 0.4.21 |  | defect | **Keep the mobile nav reachable at 860px and narrower on an engine without `:has()`, and move it off-canvas only where `:has()` works.** | 2 | 2 | 2 | 4 | 3 | 4 by 6 | 26.9 |
-| 37 | 0.4.21 |  |  | **Replace the stale architecture comment at the top of `public/css/styles.css` so it no longer says the design tokens use `light-dark()`.** | 1 | 2 | 1 | 2 | 1 | code health by 2 | 14.4 |
 | 26 | 0.4.21 |  |  | **Add a domain glossary and the project's intended horizon to the README.** | 1 | 2 | 1 | 2 | 3 | 9 by 3, code health by 2 | 11.9 |
 | 8 | 0.4.21 |  |  | **Run the visual E2E specs at viewports from a large desktop down to a small phone.** | 2 | 1 | 1 | 2 | 4 | code health by 3 | 9.0 |
 | 9 | 0.4.21 |  |  | **Typecheck `e2e-tests/` in the gate.** | 1 | 1 | 1 | 1 | 3 | code health by 2 | 9.0 |
@@ -40,23 +38,6 @@
 
 ## Details
 
-### 36. Keep the mobile nav reachable at 860px and narrower on an engine without `:has()`, and move it off-canvas only where `:has()` works.
-
-README → "Two browser floors": Chromium 87 must reach every page, and `:has()` may only decorate.
-In `public/css/styles.css`, `@media (max-width: 860px)` moves `.sidebar` off-canvas with
-`transform: translateX(-100%)`, and only `body:has(#nav-toggle:checked)` brings it and `.scrim`
-back. Below Chromium 105 (webOS TV 22 and 23) the hamburger does nothing at that width, so no page
-behind the nav can be reached. Move the off-canvas rules inside `@supports selector(:has(a))`, and
-keep the sidebar in the flow outside it, with the hamburger hidden. The desktop tree and the theme
-switch are already guarded. Test it beside `src/ui/stylesheet-floor.test.ts`.
-
-### 37. Replace the stale architecture comment at the top of `public/css/styles.css` so it no longer says the design tokens use `light-dark()`.
-
-The header (lines 4-6) says the tokens use `light-dark()`, but the TOKENS comment below it says the
-stylesheet avoids `light-dark()` and `color-scheme` for app colours, because engines resolve them
-unreliably, and maps raw `--l-*`/`--d-*` palettes in three theme blocks instead. A reader trusting
-the header looks for `light-dark()` that does not exist. Found by a comprehension-panel reader.
-
 ### 26. Add a domain glossary and the project's intended horizon to the README.
 
 Glossary: host, manifest, chrome, nav fragment, permission token, system plugin, denylist. Also the