The limit of the Willing Suspension of Disbelief for a given element is directly proportional to how pretty or stylish it is. Basically this is about making things look as appealing as poss... no, as appealing as you feel like, no matter how impossible. Want a castle made of solid pink diamond for your webcomic? Who cares about the cost, or if it's even possible to make that kind of structure. It looks pretty. Or more realistically, the royal crowns and capes. They are expensive and heavy.