Mobile-first design means building websites and apps with phones in mind first....

https://extra-wiki.win/index.php/How_Do_I_Simplify_Mobile_Navigation_Without_Hiding_Everything_in_a_Menu%3F

Mobile-first design means building websites and apps with phones in mind first. It’s all about fast loading times, easy-to-tap buttons, and simple menus that make getting around a breeze