Allow contributors to selectively add borders to images (i.e. box shadows) included in documentation on the jenkins.io site.
Main benefit in implementing this feature: Images (i.e. screenshots) with borders look nicer in documentation than those without them. Image borders create a clear distinction between written text (surrounding the images) and the images themselves, thereby improving the readability of the documentation itself. When taking screenshots for documentation (such as those in the first tutorial posted as part of the Jenkins User Documentation), the writer often needs to include a border within the image itself - as I did so in that tutorial. However, it would be better if screenshots could be taken without the need to consider including borders, and then borders added through CSS tweaks accessed through Asciidoc image reference syntax.
Implementation consideration: Here's a discussion about one such implementation of this feature.