Or you could just save your files as a png. :} Png doesn't lose any data, as opposed to a jpeg that compresses and loses some every time it is saved.

I tried, and I adore .png!

It still came out lighter than what was on my canvas.
I'm thinking it's either Photoshop's algorithms when saving as non-PSD,
or it has something to do with color bit-depth, which I should have invested
more time in learning about.

But what I really wish we could do would be to upload SVG vector files!
 alumasqrl and I have talked about doing it, and he has an example
of one he did and uploaded to his own server. It's a yellow two tone piece.
It's very cool seeing it being rastered right on the screen.