Surfing with browser set at less than 1702 pixels wide, I get a screen that says coming to mobile in the future.. get one of these other browsers.. but I'm alre

Surfing with browser set at less than 1702 pixels wide, I get a screen that says coming to mobile in the future.. get one of these other browsers.. but I'm already using firefox... so clicked to go full screen, 1920 px wide and things start happening..