No offense but I think you're probably just being paranoid (understandably of course, considering how stressful the state boards can be). The color of the screen most likely has to do with the computer itself (ie the operating system,version etc).
Don't worry! Go in calm, confident, take the test, go home.... (or do like me and go get drunk and stay hungover till I found out I passed lol)
I don't know how it is where you're taking it. But in Texas, thru Pearson Vue, we can pay $8 and find out pass or fail after 48hrs. It also shows up on the State BON website under License Verification.