Unwanted border added to images in published content

[JaniceManwiller]

In the published content, it looks like GitBook is adding a border to all of the images. This isn't as noticeable in most screenshots, which are rectangular to begin with, but is very distracting for diagrams.

For example, here is a diagram image in GitBook:

And here is the same image in the published version:

I wouldn't object to borders if they were configurable, but there doesn't seem to be any way to remove them.