Add option to keep individual document header images proportional across screen sizes

When you add an individual header image to a published Knowledge base article, the image will shift depending on the end user's monitor and screen size, sometimes covering up important visuals.

There is a "Proportional" option for the overall KB banner that locks the proportions across screen sizes, but nothing like that for individual headers. It would be helpful to have a similar option or another solution for individual header images as well.