feat: modernize ui (#381)

Co-authored-by: Elias Schneider <login@eliasschneider.com>

frontend/src/lib/components/ui/card/card-content.svelte

@@ -1,6 +1,6 @@
 <script lang="ts">
-	import type { HTMLAttributes } from 'svelte/elements';
 	import { cn } from '$lib/utils/style.js';
+	import type { HTMLAttributes } from 'svelte/elements';
 
 	type $$Props = HTMLAttributes<HTMLDivElement>;
 
@@ -8,6 +8,6 @@
 	export { className as class };
 </script>
 
-<div class={cn('p-6 pt-0', className)} {...$$restProps}>
+<div class={cn('bg-muted/20 p-6 pt-5 peer-[.card-header]:border-t', className)} {...$$restProps}>
 	<slot />
 </div>