Images aren't displayed correctly in READMEs using asciidoc.

Summary

Images displayed in .adoc (asciidoc) files aren't rendered correctly in file previews.

Steps to reproduce

Push a .adoc file (i.e. README.adoc) to a repo with an image loaded using the image::local/path/to/image.png[caption] syntax.

Example Project

Here is one on GitLab, displays both a .png and .jpg: asciidoc-image-rendering.

The same project mirrored on GitHub (displays correctly): asciidoc-image-rendering

What is the current bug behavior?

README files using asciidoc with linked images won't display them correctly in previews, they go outside the bounds.

What is the expected correct behavior?

That the images stay within the bounds of the preview.

Relevant logs and/or screenshots

Here is how it looks on GitLab:

and here's how it looks on GitHub:

Output of checks

This bug happens on GitLab.com

Possible fixes

Not sure if this is the reason, but it might be something to do with the CSS styling that GitLab uses for asciidoc. Example screenshot (the width: 100%; is new):