use bs4

src/client/styles/scss/_search.scss

@@ -32,8 +32,9 @@
   .rbt-menu {
     max-height: none !important;
     margin-top: 3px;
+    @extend .dropdown-menu-right;
+    @extend .dropdown-menu-md-left;
     @include media-breakpoint-down(sm) {
-      right: 0;
       left: auto !important;
       width: 90vw;
     }