It's a great start! I'm constantly amazed and appreciative of the talent and helpfulness of our community
A couple things I noticed on a quick run-through:
* There's a bit of a mismatch between color palette and how it gets applied to the decal and the sail. Compare the reds on the attached.
* There's no "cancel" for the color picker
* While the opacity slider can be helpful for those designing a decal, its presence in the current preview tool has unfortunately caused a lot of confusion. It would be wonderful if you noted it was for preview purposes only, or
*Not an actual game feature or the like.
Lastly, I just want to note I changed the title of this thread to note it's an unofficial tool, just to prevent any confusion. Rest assured, it has my personal sponsorship and I'll hope to be in touch soon with some of the technical details you requested.
Keep up the fabulous work!