added basic stylesheets

frontend/index.html

@@ -4,6 +4,7 @@
 <head>
     <meta charset="UTF-8" />
     <meta content="width=device-width, initial-scale=1.0" name="viewport" />
+    <link href="./index.css" rel="stylesheet" />
     <title>yellowjacket</title>
 </head>
 <script src="/index.ts" type="module"></script>