be tabbable by the user.

It's likely that either a non-interactive element was given a `tabindex` value of 0 or greater, or assigned an element’s role incorrectly. 
The Checker detects implied roles of interactive HTML elements that automatically get keyboard focus. 
The Checker also detects content blocks that get keyboard focus to enable scrolling of the area using arrow keys when coding CSS `overflow: scroll` or `overflow: auto`. 
Both of these situations are valid. 
However, if the element *should no