Fix transition covering More download options btn (#1736)

This pushes bottom transition to a background level while setting it so
that any z-indexes are isolated within the hero to avoid any other
weirdness from happenning.

pages/app.vue

@@ -1006,6 +1006,7 @@ useSeoMeta({
   align-items: center;
   text-align: center;
   flex-direction: column;
+  isolation: isolate;
 
   .main-subheader {
     font-size: 1.625rem;
@@ -1041,6 +1042,10 @@ useSeoMeta({
     mask-image: none;
     z-index: 1;
   }
+
+  .bottom-transition {
+    z-index: -1;
+  }
 }
 
 .main-header {