When the Safari browser puts a webcam video full-screen and then
returns, the z-index of the video was higher than the buttons and
controls normally overlaid on top of it.
Add a z-index:1 to the video controls to keep them on top after
returning from full screen. Similar: for popped-out draggable videos,
adding a z-index:1 allows the video to correctly sit on top of docked
videos without the docked video controls (zi:1) rendering above the
popped-out video when you overlap them.
Note: the z-index:1 is applied to popped-out and video controls, any
other combination (e.g. 1 for popped-out and 2 for controls) caused
controls of docked videos to render on top of popped-out ones when they
overlapped.
