Mobile-first design means creating apps and sites that work great on your phone...

https://wiki-square.win/index.php/What_is_Appropriate_Contrast_and_How_Do_I_Check_It_Fast%3F

Mobile-first design means creating apps and sites that work great on your phone right from the start. It focuses on fast loading, easy-to-tap buttons, and simple menus you can use on the go