GitHub link image not shown, HTML validity (missing doctype)
Thanks, just the tool I was looking for (client-side, JS only) to embed my favicon.
With Firefox 49.0.1 on Windows the image https://s3.amazonaws.com/github/ribbons/forkme_left_darkblue_121621.png is reduced to an invisible 1x1 image in cache, although if I (re-)load this file directly, it is properly displayed. This seems to be caused by the img tag not being closed (https://github.com/jpillora/base64-encoder/blob/gh-pages/index.html#L58).
The validators don't catch this at first because the HTML is slightly off: Auto-detect type: https://validator.w3.org/check?uri=http%3A%2F%2Fjpillora.com%2Fbase64-encoder%2F&charset=%28detect+automatically%29&doctype=Inline&group=0
HTML5:
https://validator.w3.org/nu/?doc=http%3A%2F%2Fjpillora.com%2Fbase64-encoder%2F
So you might want to add <!DOCTYPE html>.