feat: stick discussion sidebar to top (#1290)

src/courseware/course/new-sidebar/sidebars/discussions-notifications/DiscussionsNotificationsSidebar.jsx

@@ -17,7 +17,7 @@ const DiscussionsNotificationsSidebar = () => {
     <SidebarBase
       ariaLabel={intl.formatMessage(messages.discussionNotificationTray)}
       sidebarId={ID}
-      className="d-flex flex-column flex-fill"
+      className="d-flex flex-column flex-fill sticky-top vh-100"
       showTitleBar={false}
       showBorder={false}
     >

src/courseware/course/sidebar/sidebars/discussions/DiscussionsSidebar.jsx

@@ -32,7 +32,7 @@ const DiscussionsSidebar = ({ intl }) => {
     >
       <iframe
         src={`${discussionsUrl}?inContextSidebar`}
-        className="d-flex w-100 h-100 border-0"
+        className="d-flex sticky-top vh-100 w-100 border-0"
         title={intl.formatMessage(messages.discussionsTitle)}
         allow="clipboard-write"
         loading="lazy"

src/index.scss

@@ -368,6 +368,11 @@
   }
 }
 
+.sticky-top {
+  position: sticky;
+  top: 0;
+}
+
 // Import component-specific sass files
 @import "courseware/course/celebration/CelebrationModal.scss";
 @import "courseware/course/sidebar/sidebars/notifications/NotificationIcon.scss";