diff --git a/public/index.html b/public/index.html
index 6652c7dd60ad34f6d80148f3c8e6876702d19854..7d2fe4b28b2bfbf86d4294d9feb99308b06efb0f 100644
--- a/public/index.html
+++ b/public/index.html
@@ -1,23 +1,28 @@
-<!DOCTYPE html>
+<!doctype html>
 <html>
-  <head>
-    <meta charset="utf-8">
-    <meta name="generator" content="GitLab Pages">
-    <title>Plain HTML site using GitLab Pages</title>
-    <link rel="stylesheet" href="style.css">
-  </head>
-  <body>
-    <div class="navbar">
-      <a href="https://pages.gitlab.io/plain-html/">Plain HTML Example</a>
-      <a href="https://gitlab.com/pages/plain-html/">Repository</a>
-      <a href="https://gitlab.com/pages/">Other Examples</a>
-    </div>
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport"
+        content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
+  <title>Cube Demo</title>
 
-    <h1>Hello World!</h1>
+  <!-- three.js -->
+  <script src="https://unpkg.com/three@0.126.0/build/three.js"></script>
+</head>
+<body>
 
-    <p>
-      This is a simple plain-HTML website on GitLab Pages, without any fancy static site generator.
-    </p>
-  </body>
-</html>
+<!-- Starting an immersive WebXR session requires user interaction.
+    We start this one with a simple button. -->
+<button onclick="activateXR()">Start Cube Demo</button>
+<script>
+async function activateXR() {
+  // Add a canvas element and initialize a WebGL context that is compatible with WebXR.
+  const canvas = document.createElement("canvas");
+  document.body.appendChild(canvas);
+  const gl = canvas.getContext("webgl", {xrCompatible: true});
 
+  // To be continued in upcoming steps.
+}
+</script>
+</body>
+</html>
