added disclaimer

src/App.svelte

@@ -4,14 +4,16 @@
   import DecryptButton from './lib/DecryptButton.svelte';
   import { errorMessage } from './lib/generalStore';
   import Footer from './lib/Footer.svelte';
+    import Disclaimer from './lib/Disclaimer.svelte';
 
-  let errorMessageContent
+  let errorMessageContent: string;
   errorMessage.subscribe( value => {
     errorMessageContent = value;
   });
 </script>
 
 <main>
+  <Disclaimer />
   <h1>Encrypt and decrypt files</h1>
   {errorMessageContent}
 

src/lib/Disclaimer.svelte

@@ -0,0 +1,20 @@
+<style>
+  div.disclaimer {
+    background-color: rgb(129, 0, 0);
+    color: #fff;
+    height: 6em;
+    padding-left: 1em;
+    padding-right: 1em;
+    padding-bottom: 3px;
+    padding-top: 5px;
+    left: 0;
+    position: absolute;
+    right: 0;
+    top: 0;
+  }
+</style>
+
+<div class="disclaimer">
+  <h3>DISCLAIMER</h3>
+  <p>This Webapp is not yet ready for production and should not be relied on to be cryptographically secure</p>
+</div>