adjust templates, add timezone and locale

app/views/send_submission_email/success.html.erb

@@ -1 +1,18 @@
-Email has bee sent
+<div class="max-w-md mx-auto px-2 mt-12 mb-4">
+  <div class="space-y-6 mx-auto">
+    <div class="space-y-6">
+      <div class="flex items-center justify-center">
+        <a href="/" class="flex items-center">
+          <div class="mr-3">
+            <%= render 'shared/logo', width: '50px', height: '50px' %>
+          </div>
+          <h1 class="text-5xl font-bold text-center">DocuSeal</h1>
+        </a>
+      </div>
+      <div class="text-center text-4xl font-bold">
+        Email has been sent
+      </div>
+    </div>
+  </div>
+</div>
+<%= render 'shared/attribution' %>