diff --git a/addons/website_slides/static/src/js/slides_course_page.js b/addons/website_slides/static/src/js/slides_course_page.js
index e0d6bc5d50e..c82f1b18ead 100644
--- a/addons/website_slides/static/src/js/slides_course_page.js
+++ b/addons/website_slides/static/src/js/slides_course_page.js
@@ -35,22 +35,6 @@ export const SlideCoursePage = publicWidget.Widget.extend({
         }
     },
 
-    /**
-     * @override
-     */
-    start: function () {
-        // TODO: we need to clean this code and make the changes in the view in master
-        const $completed = $('.o_wslides_channel_completion_completed');
-        const $progressbar = $('.o_wslides_channel_completion_progressbar');
-        if($progressbar.hasClass('d-none')){
-            $progressbar.removeClass('d-none').addClass('d-flex').addClass('hidden-progressbar-completed-tag');
-        }
-        if($completed.hasClass('d-none')){
-            $completed.removeClass('d-none').addClass('hidden-progressbar-completed-tag');
-        }
-        return this._super.apply(this, arguments)
-    },
-
     /**
      * Greens up the bullet when the slide is completed
      *
@@ -90,12 +74,12 @@ export const SlideCoursePage = publicWidget.Widget.extend({
 
         if (completion < 100) {
             // Hide the "Completed" text and show the progress bar
-            $completed.addClass('hidden-progressbar-completed-tag');
-            $progressbar.removeClass('hidden-progressbar-completed-tag');
+            $completed.addClass('d-none');
+            $progressbar.removeClass('d-none').addClass('d-flex');
         } else {
             // Hide the progress bar and show the "Completed" text
-            $completed.removeClass('hidden-progressbar-completed-tag');
-            $progressbar.addClass('hidden-progressbar-completed-tag');
+            $completed.removeClass('d-none');
+            $progressbar.addClass('d-none').removeClass('d-flex');
         }
 
         $progressbar.find('.progress-bar').css('width', `${completion}%`);
diff --git a/addons/website_slides/static/src/scss/website_slides.scss b/addons/website_slides/static/src/scss/website_slides.scss
index 6871271e2c1..cbc2c97cac3 100644
--- a/addons/website_slides/static/src/scss/website_slides.scss
+++ b/addons/website_slides/static/src/scss/website_slides.scss
@@ -617,11 +617,10 @@ $line-height-truncate: 1.25em;
     }
 }
 
-.hidden-progressbar-completed-tag {
-    visibility: hidden;
-    @include media-breakpoint-down(sm) {
-        display: none !important;
-    }
+// Enforce the height of the lesson header, so the DOM element size do not change
+// when the completion progressbar become visible / hidden
+.o_wslides_lesson_header_container {
+    height: 80px;
 }
 
 .o_wslides_fs_sidebar_section {