minor demo fix for fallback mode (inline style was overriding plyr stylesheet)

demo/index.html

@@ -184,9 +184,11 @@
                     <!-- BEGIN FULLSCREEN OVERLAY EXAMPLE -->
                     <style>
                         #container {
+                            overflow: hidden;
+                        }
+                        #container:not(.plyr--fullscreen-fallback) {
                             position: relative;
                             margin-top: 16px;
-                            overflow: hidden;
                         }
                         .plyr {
                             margin-top: 0;