linkear el main.js

app/index.php

@@ -23,6 +23,6 @@ $nombre = "Norberto Montalvo García";
     <button class="down" onclick="disminuir()">Disminuye</button>
 </div>
 
-<script src="main.js" type="module"></script>
+<script src="main.js?a=2"></script>
 
 </html>