update from upstreamHEADmaster

1 files changed, 3 insertions, 1 deletions

diff --git a/src/js/fullscreen.js b/src/js/fullscreen.js
index 20e958fc..c1feadb5 100644
--- a/src/js/fullscreen.js
+++ b/src/js/fullscreen.js
@@ -124,7 +124,9 @@ class Fullscreen {
       return hasClass(this.target, this.player.config.classNames.fullscreen.fallback);
     }
 
-    const element = !this.prefix ? document.fullscreenElement : document[`${this.prefix}${this.property}Element`];
+    const element = !this.prefix
+      ? this.target.getRootNode().fullscreenElement
+      : this.target.getRootNode()[`${this.prefix}${this.property}Element`];
 
     return element && element.shadowRoot ? element === this.target.getRootNode().host : element === this.target;
   }