problem:
The keyboard layouts main image, is displayed as a black rectangle, when the
readme.org file, it's opened in Spacemacs. This seems to be because there's an
issue with the transparency when a .png is saved with indexed colors.
When the transparency issue is fixed, by re-saving it as a non-indexed
(grayscale or RGB) image. Then there still is an issue, with themes that have a
dark background, i.e. spacemacs-dark. The black keys become almost invisible.
solution:
Add a 1px gray border, around the keys.