Blank white skin loading as black

I discovered for the first time how to customize skins, so I went to a external website for making skins. I thought that it would be funny to go to a public server (Hypixel.net) with a completely white skin. I painted the whole 3D model in the website white, loaded the skin in the launcher, and joined. I then pressed F5 to see what I looked like, and i was completely black. I do understand that painting the model white created a blank .jpg file, and the game registered it as if there was nothing there, but it should still paint the skin white, not black...