My blog has a fixed width, and uses internal side-to-side scrolling for fenced code blocks (overflow-x: auto.) Unfortunately, this creates an accessibility violation! You can read about it here: https://dequeuniversity.com/rules/axe/3.5/scrollable-region-focusable?application=axeAPI
The fix here is to add tabindex="0" to the pre elements. I can do this myself with a regular expression, of course, but is there a way to override the output during generation?