diff --git a/03 - CSS Variables/index-START.html b/03 - CSS Variables/index-START.html
index 8a4f0d556e..250c253239 100644
--- a/03 - CSS Variables/index-START.html	
+++ b/03 - CSS Variables/index-START.html	
@@ -22,6 +22,21 @@ <h2>Update CSS Variables with <span class='hl'>JS</span></h2>
 
   <style>
 
+    :root {
+      --base: #ffc600;
+      --spacing: 10px;
+      --blur: 10px;
+    }
+
+    img {
+      padding: var(--spacing);
+      background: var(--base);
+      filter: blur(var(--blur));
+    }
+
+    .hl {
+      color: var(--base);
+    }
     /*
       misc styles, nothing to do with CSS variables
     */
@@ -45,6 +60,17 @@ <h2>Update CSS Variables with <span class='hl'>JS</span></h2>
   </style>
 
   <script>
+
+    const inputs = document.querySelectorAll('.controls input');
+
+    function handleUpdate() {
+      const suffix = this.dataset.sizing || '';
+      document.documentElement.style.setProperty(`--${this.name}`, this.value + suffix);
+    }
+
+    inputs.forEach(input => input.addEventListener('change', handleUpdate));
+    inputs.forEach(input => input.addEventListener('mousemove', handleUpdate));
+
   </script>
 
 </body>