How to listen to music on youtube while on other apps/with the screen off on android!

Idk if this works on iphone but what you gotta do is download firefox and then just head to youtube.com as normal except you're gonna make sure ur in desktop mode and when the video starts playing exit out and swipe down so you have like the menu thing and make sure to click play in case it stopped ok bye give kudos to let me know if it worked