On Beeminder.com, a new user is currently show the "classic" button style, of yellow letters, all caps, on a black background. I've set up an A/B test framework to try a "modern" style that is black text on yellow background, mixed case, with more rounded corners on the buttons. Will the new buttons be statistically significantly better than the old ones? (We use a Monte-Carlo simulation sampling from the posterior beta distributions for conversion rates for classic and modern styles, and "significantly better" means the MC simulation for one style beats the other 95%+ of the time)