reconfigure css to allow consumer styling

It's a little jank, but it works. The consumer absolutely MUST have a
file at `$lib/styles/tailwind.css` that contains all necessary tailwind
imports AND also imports the `src/lib/styles/base.css` file from sui.

WILL address this in another commit.

src/lib/DateInput.svelte

@@ -311,7 +311,7 @@
 {/snippet}
 
 <style lang="postcss">
-	@reference "./styles/theme.css";
+	@reference "$lib/styles/tailwind.css";
 
 	.date-input {
 		@apply ring-sui-accent dark:ring-sui-accent/50 h-6 min-w-[1ch] outline-0 transition-all focus:ring-2;