Reduce excessive empty space across all website pages

Adjust vertical padding and margins on various pages and the footer to decrease whitespace, improving layout density on both desktop and mobile.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 23852c00-4779-460a-9e0c-d09fee4b6c92
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Event-Id: 1a3c4949-1987-4937-a1b8-d66e3d8b8bb1
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/f209e72a-0939-48fa-84fc-57854de71967/23852c00-4779-460a-9e0c-d09fee4b6c92/ee1CXlO
Replit-Helium-Checkpoint-Created: true

client/src/pages/article.tsx

@@ -220,16 +220,16 @@ export default function ArticlePage() {
     <div className="min-h-screen bg-background">
       <Header />
       <PageSideAds />
-      <main className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-8">
+      <main className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-4">
         <Link href="/">
-          <Button variant="ghost" size="sm" className="mb-6 gap-2" data-testid="button-back">
+          <Button variant="ghost" size="sm" className="mb-4 gap-2" data-testid="button-back">
             <ArrowLeft className="w-4 h-4" />
             Zurück
           </Button>
         </Link>
 
         {article.coverImage && (
-          <div className="relative overflow-hidden rounded-md mb-8">
+          <div className="relative overflow-hidden rounded-md mb-6">
             <img
               src={article.coverImage}
               alt={article.title}