feat: add position relative to .app-main

src/scss/_app-main.scss

@@ -2,6 +2,7 @@
   grid-area: #{$lte-prefix}app-main;
   max-width: 100vw;
   padding-bottom: 1rem;
+  position: relative;
   @include transition($lte-transition-speed $lte-transition-fn);
 
   .app-content-header {