Mobile-first design means building your app or website for phones first, so it...

https://source-wiki.win/index.php/How_to_Design_a_Mobile_Menu_That_Does_Not_Feel_Like_a_Maze

Mobile-first design means building your app or website for phones first, so it loads fast and feels easy to use. Buttons and menus are big enough to tap with your thumb, and pages are simple to move through