B2B-88: add starter kit structure and elements

app/(marketing)/_components/site-page-header.tsx

@@ -0,0 +1,37 @@
+import { cn } from '@kit/ui/utils';
+
+export function SitePageHeader({
+  title,
+  subtitle,
+  container = true,
+  className = '',
+}: {
+  title: string;
+  subtitle: string;
+  container?: boolean;
+  className?: string;
+}) {
+  const containerClass = container ? 'container' : '';
+
+  return (
+    <div className={cn('border-b py-8 xl:py-10 2xl:py-12', className)}>
+      <div className={cn('flex flex-col gap-y-3 lg:gap-y-4', containerClass)}>
+        <h1
+          className={
+            'font-heading text-3xl font-medium tracking-tighter xl:text-5xl dark:text-white'
+          }
+        >
+          {title}
+        </h1>
+
+        <h2
+          className={
+            'text-muted-foreground text-lg tracking-tight 2xl:text-2xl'
+          }
+        >
+          {subtitle}
+        </h2>
+      </div>
+    </div>
+  );
+}