diff --git a/index.html b/index.html
index ac7a1cb..45e21e7 100644
--- a/index.html
+++ b/index.html
@@ -9,6 +9,15 @@
 :root {
   --aside-size: 218px;
 }
+.js {
+  display: none;
+}
+noscript {
+  padding: 10px;
+}
+a {
+  color: cornflowerblue;
+}
 body {
   padding: 0;
   margin: 0;
@@ -57,7 +66,7 @@ aside > container > div {
 </style>
 </head>
 <body>
-<aside>
+<aside class="js">
 <container>
 <div style="width:100%">
 <button onclick="toggle_physics()">Physics</button>
@@ -92,7 +101,13 @@ aside > container > div {
 </aside>
 <main>
 </main>
+<noscript>
+This page requires JavaScript.
+<br>
+Source code: <a href="https://git.atomic.garden/root/sphere-charges">https://git.atomic.garden/root/sphere-charges</a>
+</noscript>
 <script src="thomson-problem.js"></script>
 <script src="sketch.js"></script>
+<script>document.querySelectorAll(".js").forEach(e => e.style = "display:initial");</script>
 </body>
 </html>
