feat: add consistent border styling and improve layout spacing

- Applied border-gray-200 borders to main sections for visual consistency
- Restructured HomeTab component with full-width card grid layout
- Refined spacing and padding across hero, benefits, and hosting sections

src/components/Header.tsx

@@ -27,8 +27,8 @@ export function Header() {
 
   return (
     <header className="bg-transparent">
-      <nav>
-                <Container className="flex bg-transparent justify-between py-4">
+      <nav className="border-b border-gray-200">
+        <Container className="flex bg-transparent justify-between py-4">
           <div className="relative z-10 flex items-center gap-16">
             <Link to="/" aria-label="Home">
               <img src={pmyceliumLogo} alt="Mycelium" className="h-8 w-auto" />