Images
Images should be retina-friendly
Banner Images (image): 540px x 540px
Gallery images (gallery): 840px wide
Video embeds
Copy and paste the video embed into any text field
<iframe width="420" height="315"
src="https://www.youtube.com/embed/dQw4w9WgXcQ"
frameborder="0" allowfullscreen>
</iframe>