Please refer to >>490 and report any issues in the same thread
The background of the thumbnail for my image posted is black even tho its supposed to be transparent. The big image is fine.
This is caused by using JPG thumbnails. I will switch to PNG to support transparency.
The old images will still have black background, but new posts will support transparent background.
Will report back when fixed.
Should be fixed from now on, and I fixed your image as an example.