How does your site make money? What is the house edge?
The house edge is based on the payment system.
If you have a 7, then it can be
:high (47%)
:low (47%)
:7 (6%)
And he pays you:
:high (47%) 1.9
:low (47%) 1.9
while he must pay:
:high (47%) 2.1
:low (47%) 2.1
The game could be probability fair, but the payments are not, and that is the house edge.
What about matching the color or the suit?
Its simple. The color can be RED or BLACK. So 50/50. You should win 2.00 but you win 1.90.
The suit is the same, but with 4, so 25/25/25/25, and should pay 4.00, but pays 3.85.
cards are randomed before game starts 