Black border around images and videos
In the case that your feed starts to show black borders around your images and/or videos, the most likely cause is theme compatibility.
Some themes apply their own styling to images that may conflict with Spotlight's feed display.
For example, we encountered a theme that set an image's max-width to 50%, causing a thick black border to replace the other 50% of the space typically used by the rest of the image.
Some CSS will be able to fix this issue, but it's best to contact your theme developer to ensure that you use the correct code and not affect any other parts of your theme.