Give the popup window a z-index of 10

src/routes/popup/+page.svelte

@@ -11,6 +11,7 @@
       background-color: rgba(0, 0, 0, 0.125);
       font-family: Noto Sans, sans serif;
       color: white;
+      z-index: 10;
 
       .nc-popup-inner {
         display: block;