Test in as many browsers as feasible. As usual, it probably helps to have the JS console open. In desktop browsers: Ensure that the browser window is as large as possible Open a course Open the module chooser Confirm it's centered Confirm that the page does not scroll Resize the page to a size slightly smaller than the chooser is currently Confirm that the chooser scales as required Confirm that the page still does not scroll Resize the page to a pretty tiny size - until the button disappear from the chooser Confirm that the chooser scales as required Confirm that the page now supports scrolling so that you can view the buttons Resize the page up again Confirm that the chooser scales as required Confirm that the page no longer scrolls Resize the page down again and refresh the page Confirm that the chooser scales as required Confirm that the page supports scrolling so that you can view the buttons In a mobile browser (I only have iOS to hand): Open Safari in portrait mode Open a course Open the module chooser Confirm it's centered Note: Scrolling currently does work on mobile devices Change to landscape orientation Confirm that the chooser re-centers Change back to portrait orientation Confirm that the chooser re-centers