site: a lit hero, new slogans, the wallpapers, and a better reader

Home:
- The hero stands on a light from the upper left and a pool of the
  accent, mixed from Niveus tokens so it follows the theme. The mark sits
  in an .nv-tile key under a slogan: "Every layer its own -- from the
  first instruction to the last pixel."
- New section headings: "A teaching kernel that outgrew its lessons",
  "Measured, not marketed", "One ISO. One stick. Your disks untouched."
- A Wallpapers section with the four new ones, each downloadable as a
  4K JPEG or as SVG. The four-card grids are two across, so none is left
  alone on its row.

Docs reader:
- An index filter, a breadcrumb with reading time and source path,
  code blocks framed with a language strip and a Copy key, previous and
  next keys at the foot, a reading-progress hairline, and the contents
  entry lit for the section on screen.
- The index lists the documents it was missing: scheduler, FAT, audio,
  LDLS, debugging and the hardware report.
- On a phone the page is no longer wider than the screen (a pre block
  was sizing the grid's auto column), and the index folds away.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4

docs/Website/docs.html

@@ -52,13 +52,23 @@
   </div>
 </nav>
 
+<div class="readbar" aria-hidden="true"><span id="readbar"></span></div>
+
 <!-- Index, document, contents. Three columns that become one on a narrow
      screen, in that order, because that is their order of importance when
      there is only room for the middle one. -->
 <div class="docshell">
   <aside class="docshell__aside" aria-label="Documentation index">
-    <nav class="nv-nav nv-nav--vertical nv-nav--static docnav" id="docnav"
-         style="--nv-selection-name: nv-docs-index"></nav>
+    <details class="nv-disclosure nv-disclosure--plain docindex" id="docindex" open>
+      <summary class="nv-button nv-button--sm nv-disclosure__summary">All documents</summary>
+      <div class="docfind">
+        <label class="nv-visually-hidden" for="docfilter">Filter documents</label>
+        <input class="nv-input nv-input--sm" id="docfilter" type="search"
+               placeholder="Filter documents…" autocomplete="off">
+      </div>
+      <nav class="nv-nav nv-nav--vertical nv-nav--static docnav" id="docnav"
+           style="--nv-selection-name: nv-docs-index"></nav>
+    </details>
   </aside>
 
   <main class="docshell__main">