moved to multi-file, added some comments

index.html

@@ -24,9 +24,9 @@
         <input type="number" id="np" min="3" ><br>
         <label for="steps">Number of steps: </label>
         <input type="number" id="steps" min="10" /><br>
-        <button onclick="generatePanel()">Generate!</button>
+        <button id="generate">Generate!</button>
         <p id="len"></p>
         <div id="output"></div>
-        <script src="index.js" lang="js"></script>
+        <script src="src/main.js" lang="js" type="module"></script>
     </body>
 </html>