What is a "neutral card"?

[aversethule]

There is an upgrade that allows one to reduce the cost of renewing neutral cards in the tent to 0 rest points, yet I cannot find anywhere in the game a definition of what a "neutral card" is.

[Fringehunter7719]

Cards with grey backgrounds as opposed to red ones. These include cards like potions and bleeds.

One supposes that when the further characters are implemented they will be themed with a colour and a unique deck relating to their attribute, be it earth, ice, or whatever that corresponds with Lucia's red/fire.

In similar games, such as Slay the Spire, this is what happens and each character can principally recruit from their own deck or the neutral deck and barring exceptional cases cannot access the other colours.