Am I Missing Something Here?

Last night a buddy of mine showed me a side bet you can make on Party Poker. Before you see any cards you can make a side bet on whether the flop will be all red or all black (you choose one). The payout is 8:1 but I calculated that the odds against this bet to be 7.5:1. Is there something wrong with my math? I can't imagine Party would give you the odds to make this bet. Or is Party only giving you 7:1 on your money and is including your bet as part of the payout?