What Do the Colors of the Cards Mean?

So each card has a specific colored border around it, but what does each one mean? Some of the colors seem kind of random, like blue or brown. Thanks for any and all help!

Green ones are team cards, the pink ones are infinite cards.


And the red ones can be send twice. Also Germans have 5 jaegers that is an infinite-team card, this one has both borders
There was a infinite gold crates shipment that hadnt the purple border idk if it was fixed
Blue is for age up cards from USA and africans.


I think iĀ“ve seen blue in the travois cards of the haudenosauneeā€¦

It used to be green (team), purple (infinite) and red (twice for japs), but now thereā€™re more card colors: yellow (economic/upgrades), white (units), brown (defense wagons) and blue (special abilities or travois)

Thereā€™re also mixtures of them, some doesnā€™t have sense.