So you have to create the game with a lot of different resolutions and screen ratios in mind, or you can just make your game responsive
"When you are about to create an HTML5 game, you should know most of your players will come from mobile devices. Most – if not all – sponsors look at an HTML5 game only if it perfectly fits in a wide range of mobile phones and tablets, and most – if not all – of them do not like black letterbox bars when your game size ratio does not match the size ratio of the mobile device it’s working on."
"So you have to create the game with a lot of different resolutions and screen ratios in mind, or you can just make your game responsive."
