Update CSS in email templates

Enhanced the design of the 'invite-user' and 'confirm-email' templates by adding new CSS code. This CSS code professionaly styles the email, improving readability and user experience.

packages/email-templates/src/components/body-style.tsx

@@ -0,0 +1,16 @@
+import * as React from 'react';
+
+export function BodyStyle() {
+  return (
+    <style>
+      {`
+        body {
+          background-color: #fff;
+          margin: auto;
+          font-family: sans-serif;
+          color: #484848;
+        }
+    `}
+    </style>
+  );
+}