When I needed to change dimensions, I started over. The first step did show 0/8 but the fractions of the inch were present on the second step.
Edit: Now that I've been through the process, I also found that your pricing was $14USD more for the same materials and dimensions than the first site that came up when I searched "online framing" ($46 vs $32). Its not clear from your site how you differentiate on that markup.