Wow I must say free gradient for EVERYONE!1!1!1! (If you wanna use this as a background in ur deck, make sure to delete the collision on the deck actor's collision. This was taught by @Sunkern)
how it works: portals show an png/jpeg thumbnail of the deck when you do it small and resize it in new decks you'll get a lower quality version of the original if well makes the ilussion of a radial gradient