Hi Melcher, Firefox's built-in PDF viewer is not as advanced as Adobe Reader or other PDF viewers, and it sometimes shows things that -- if it were fully compliant -- it should not show, like hidden layers.

Over time, these bugs are swatted one by one, but progress can be slow for uncommon issues.

Do you want to share a link to that PDF, if it's on a public site, for someone to take a closer look?

Sure. It’s available here: https://cvmg.ca/resources/Au83gabGuDEC94zz/2019/CVMG%20News-5201-Jan%202018.pdf

To see a similar file that doesn’t do the boxes, try this one: https://cvmg.ca/resources/Au83gabGuDEC94zz/2018/CVMG%20News-5112-Dec-2018.pdf

Hi Melcher, I think it's a combination of things: differences between the two converters, and between Firefox and Acrobat.

The more recent newsletter has clickable hotspots (in Firefox's viewer, these are called link annotations), and the older newsletter does not. This probably is a difference between Xara (preserves links) and Distiller (does not preserve links).

Firefox's viewer has a built-in style rule to show a solid 1px black border around link annotations, and a yellow background when they are hovered with the mouse. I don't think there is a way to avoid or influence that in the current design.

It would be more aesthetically appealing for the viewer to show a light dotted outline, or no outline until hovered, but I don't know whether that would be considered for urgent implementation (i.e., within 3-6 months). You can file a new issue here to start the conversation:

https://github.com/mozilla/pdf.js/issues

(As an aside, the new file name should have Jan 2019.)