Outer margin 5% in from each edge. The B&H Logo, sponsors, location marker, QR code and date align to it. On the Poster: 96 px left and right, 118 px top and bottom.
Inner margin 10% in from each edge, used where social UI covers the edges, like the logos and marker on Vertical no QR. On the Poster: 194 px left and right, 237 px top and bottom.
In Illustrator These match the video safe areas (Artboard Options › Show Video Safe Areas), so the guides are already on every board.
Gradient
Starting point A black fade over the bottom of the hero image: 0% at the top to 100% black (#000000) at the bottom, midpoint 50%, about the bottom 36% of the artboard and full width. It sits above the hero image and below everything else.
Then adjust Judge it against the hero image. Change the height and opacity, or duplicate it to the top when the image needs it. The fade should support the type without dulling the photo.
Store Wayfinder Always gets two: a top fade and a bottom fade.