How to bring the Player to front on Samsung Legacy TV App?

Hi currently, I am on developing app for Samsung Legacy Smart TV, but I have an issue when playing Video where the player appears behind UI, I’ve tried change the z-index on CSS style for id pluginPlayer, but it does not change anything. the player still behind the UI.

Here is the image of my testing app.

How to make the video player go to front?

Please help and thank you.