Fix: full-width layout for pages without sidebar

Added CSS rule .no-sidebar .content-wrapper { grid-template-columns: 1fr }
to make content full-width when no sidebar is present.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Assets/css/style.css

@@ -341,6 +341,11 @@ img {
   .content-wrapper {
     grid-template-columns: 2fr 1fr;
   }
+
+  /* Full width when no sidebar */
+  .no-sidebar .content-wrapper {
+    grid-template-columns: 1fr;
+  }
 }
 
 #primary {