fix: latex rendering issue

src/lib/components/chat/Messages/Markdown/KatexRenderer.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
 	import katex from 'katex';
 	import 'katex/contrib/mhchem';
+	import 'katex/dist/katex.min.css';
 
 	export let content: string;
 	export let displayMode: boolean = false;