Formatting for Mobile + TalentLMS

I've been working on some Storyline 360 courses recently that will be viewed almost entirely on mobile devices. 540x720 slide size (3:4 ratio) looks pretty great with the modern player on most devices while still being usable on desktop. It also looks good when embedded in TalentLMS if you're viewing through the TalentLMS app. However, if you view using the mobile browser, there appears to be some padding that causes the training to not look as good. Here are a couple of screenshots comparing the app view (top) to the mobile browser view (bottom):

Does anyone have tips for how to format to make this format function as smoothly as possible on the mobile?