Be very careful with making any facsimile too close in proportion, size or detail to actual currency.
I received a lesson in the legality of this in my very first job out of college. I made a discount coupon look entirely too much like actual currency, and it cost my employer a fair amount of money and embarassment.
Don’t worry, the background for the bill isn’t like real money. It will look less like real money than the Jorge Bush fake dollar.