adjust styling

src/lib/RadioGroup.svelte

@@ -29,11 +29,11 @@
 	const isVert = $derived(group.orientation === 'vertical');
 </script>
 
-<div class={['flex w-fit flex-col', classValue]} {...group.root}>
+<div class={[classValue]} {...group.root}>
 	{#if label}
 		<Label {...group.label}>{label}</Label>
 	{/if}
-	<div class="flex {isVert ? 'flex-col gap-1' : 'flex-row gap-3'}">
+	<div class="flex {isVert ? 'flex-col gap-1' : 'flex-row justify-center gap-3'}">
 		{#each options as opt}
 			{@const item = group.getItem(getValue(opt))}
 			<div
@@ -74,7 +74,9 @@
 		onvalidate={(e) => (valid = e.detail.valid)}
 	/>
 
-	<div class={['opacity-0 transition-opacity', !valid && 'opacity-100']}>
-		<Label for={group.label.for} error>{invalidMessage}</Label>
-	</div>
+	{#if required}
+		<div class={['opacity-0 transition-opacity', !valid && 'opacity-100']}>
+			<Label for={group.label.for} error>{invalidMessage}</Label>
+		</div>
+	{/if}
 </div>