This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
:-moz-full-screen-ancestor CSS pseudo-class is a Mozilla extension that represents all ancestors of the full-screen element, except containing frames in parent documents, which are the full-screen element in their own documents. However, those elements' ancestors have this pseudo-class applied to them.
This pseudo-class was removed in Firefox 50.
No compatibility data found. Please contribute data for "css.selectors.-moz-full-screen-ancestor" (depth: 1) to the MDN compatibility data repository.