[bug fix] navbar dropdown positioning

assets/sass/components/_search.scss

@@ -352,6 +352,7 @@
     @include themify($themes) {
       color: themed('burger-menu-color');
       background-color: themed('navbar-background-color');
+      border-bottom: 1px solid themed('navbar-border-bottom-color');
       @include on-event {
         color: themed('link-hover');   
       }

assets/sass/layout/_navigation.scss

@@ -47,6 +47,7 @@
 
     @include themify($themes) {
       background-color: themed('navbar-background-color') !important;
+      border-bottom: 1px solid themed('navbar-border-bottom-color') !important;
       @include on-event {
         background-color: themed('navbar-menu-hover-background-color');
       }
@@ -91,6 +92,7 @@
       @include justify-content(flex-end);
       @include themify($themes) {
         background: themed('navbar-background-color');
+        border-bottom: 1px solid themed('navbar-border-bottom-color');
       }
 
       span {
@@ -344,6 +346,8 @@
   }
 
   .dropdown {
+    position: relative;
+
     @include flexbox();
     @include align-items(center);
     @include justify-content(center);