Hero paragraph centers its measure box

max-width: 46ch without auto margins left-anchored the box inside the
centered column; the text centered in the wrong frame.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y42TyF8Zu7NGRR2893vNcZ

style/main.css

@@ -193,6 +193,10 @@ main.not-found {
   color: var(--ink-dim);
   font-size: 1.05rem;
   max-width: 46ch;
+  /* The measure cap shrinks the box below the copy column; without
+     auto margins the box left-anchors and its centered text centers
+     in the wrong frame. */
+  margin-inline: auto;
 }
 
 /* A content-shipped hero module (site.yaml hero.kind: module) draws