Wrong. The server seed changes upon a client seed change. This is not provably fair.

If I were to generate a new server seed upon knowing your client seed, there would be at least one corresponding pair (even with nonces) that can be created to manipulate the bets in some way. If a user is betting in a predictable fashion, this can be abused. Suppose the probability of winning is never above 50%. Then, bets that have a result around 5000 create a much higher house edge than typical random generation.

You need to show the next server seed hash.