Explore your email on different screen sizes
It may be helpful to visualize how your email looks across various screen sizes. In the upper right corner of the Preview, click the Layout button and then select Grid. You'll have the option to create separate previews with common device screen sizes. Note that these "device" previews are actually just previews rendered at the specified screen dimensions.
All of the previews will update automatically whenever changes are made to the email. You can view previews for HTML, Text, or AMP by switching to that tab - the previews will update to match.
Rearrange the previews however you'd like.
You can apply Visual Impairments, Image Blocking, and Dark Mode to each separate preview individually (with the buttons at it's border) or to all previews at once (with the buttons above the full preview window). Screenshots can similarly be taken of individual previews or all of the previews at once. If you take a screenshot of all of the previews, you'll get a zip file containing each image.