header: add two neon-green vertical rails at left/right edges of max-w-container, spanning top utility bar through browse bar (frames the whole header)

src/components/Header.tsx

@@ -243,7 +243,7 @@ export default function Header() {
   };
 
   return (
-    <>
+    <div className="bb-header-rails relative">
       {/* TOP BAR */}
       <div className="max-w-container mx-auto px-4">
         <div className="bg-[#1a2535] border-b border-[#2a3a50] h-8 flex items-center justify-between">
@@ -643,6 +643,6 @@ export default function Header() {
           </div>
         </div>
       </div>
-    </>
+    </div>
   );
 }