diff --git a/addons/website/static/src/scss/website.scss b/addons/website/static/src/scss/website.scss
index 6c04ea931ea..ffd323d8b6e 100644
--- a/addons/website/static/src/scss/website.scss
+++ b/addons/website/static/src/scss/website.scss
@@ -1222,7 +1222,7 @@ header {
 .o_mega_menu {
     width: 100%;
     padding: 0;
-    margin-top: 0;
+    margin-top: 0 !important;
     border-radius: 0;
     background-clip: unset; // Remove the 1px gap introduced by BS4
     background-color: transparent; // In order to allow the mega menu to be transparent
diff --git a/addons/website/static/tests/tours/edit_menus.js b/addons/website/static/tests/tours/edit_menus.js
index fdf5e2ae224..93bbe91df44 100644
--- a/addons/website/static/tests/tours/edit_menus.js
+++ b/addons/website/static/tests/tours/edit_menus.js
@@ -240,6 +240,11 @@ wTourUtils.registerWebsitePreviewTour('edit_menus', {
         content: "When the mega menu is opened, scroll up",
         trigger: 'iframe #top_menu .o_mega_menu_toggle.show',
         run: function () {
+            const marginTopOfMegaMenu = getComputedStyle(
+                this.$anchor[0].closest('.dropdown').querySelector('.o_mega_menu'))['margin-top'];
+            if (marginTopOfMegaMenu !== '0px') {
+                console.error('The margin-top of the mega menu should be 0px');
+            }
             // Scroll up.
             this.$anchor[0].closest('body').querySelector('.s_media_list_item:nth-child(2)')
                 .scrollIntoView(true);