I finished a cake last night and put it in my spare room until this morning when I dropped it off at work.

When I opened the cake box this morning - the red had bled into the white. How do I stop this happening next time. If you look in my pics you will be able to see it prior to the bleed.

I'm thinking because it was royal icing and the shortening in the fondant was breaking down the royal icing. Buttercream would have probably been a better match of ingredients, or if you could have made the design with fondant, or even just painted the fondant with food color and vodka (or a clear extract with alcohol).