docs: center landing identity and search

Author: Nomadcxx

docs-site/app/global.css

@@ -528,6 +528,7 @@ a[data-active='true'],
   display: grid;
   gap: var(--space-lg);
   width: min(100%, 58rem);
+  margin-inline: auto;
   border-bottom: 1px solid var(--color-rule);
   padding: var(--space-lg) var(--space-md) var(--space-xl);
 }
@@ -937,7 +938,7 @@ a[data-active='true'],
   }
 
   .site-header {
-    grid-template-columns: 15.5rem minmax(18rem, 42rem) minmax(9rem, 1fr);
+    grid-template-columns: minmax(0, 1fr) minmax(18rem, 42rem) minmax(0, 1fr);
     gap: var(--space-lg);
     padding-inline: var(--space-md);
   }
@@ -985,6 +986,12 @@ a[data-active='true'],
   }
 }
 
+@media (min-width: 90rem) {
+  .docs-home-hero {
+    transform: translateX(calc(var(--fd-sidebar-width) / -2));
+  }
+}
+
 @media (prefers-reduced-motion: reduce) {
   *,
   *::before,

docs-site/design.md

@@ -78,6 +78,9 @@ named tokens rather than raw spacing values.
 - The green and cyan signal roles.
 - IBM Plex Sans and Fira Code.
 - The same control geometry and focus treatment.
+- The desktop search stays centred on the visible page. The large wordmark
+  centres in the unobstructed docs canvas, then centres on the full page once
+  the viewport is wide enough to clear the persistent sidebar.
 - Stacked section headings without slash ornaments, decorative eyebrows, or
   hanging chapter labels.
 

docs-site/scripts/check-export.mjs

@@ -126,6 +126,21 @@ assert.doesNotMatch(banner, /[█▄▀]/, 'banner block art still depends on fo
 assert.match(occ, /<rect\b/, 'OCC mark has no rectangle geometry');
 assert.match(banner, /<rect\b/, 'banner has no rectangle geometry');
 assert.match(sourceCss, /designed-as-app/, 'Hallmark app-system stamp is missing');
+assert.match(
+  sourceCss,
+  /\.docs-home-hero\s*\{[^}]*margin-inline:\s*auto;/s,
+  'wordmark container is missing automatic inline margins',
+);
+assert.match(
+  sourceCss,
+  /@media\s*\(min-width:\s*90rem\)\s*\{[\s\S]*?\.docs-home-hero\s*\{[^}]*transform:\s*translateX\(calc\(var\(--fd-sidebar-width\)\s*\/\s*-2\)\);/,
+  'wide-screen wordmark does not compensate for the sidebar',
+);
+assert.match(
+  sourceCss,
+  /grid-template-columns:\s*minmax\(0,\s*1fr\)\s+minmax\(18rem,\s*42rem\)\s+minmax\(0,\s*1fr\);/,
+  'desktop search is not centred between equal outer tracks',
+);
 
 assert.ok(rootHtml.includes(`href="${basePath}/docs/"`), 'site root does not link to docs');
 assert.ok(rootHtml.includes(`url=${basePath}/docs/`), 'site root does not redirect to docs');