html – Why is this layout so slow, especially on mobile devices?

The following code uses flex to display some divs that act as buttons: it's about creating a basic layout for simple games.

There are two problems with this type of encoding: first, the speed of execution and, secondly, the management of the percentage of each container.

Style makes a difference, does the trick on a laptop, but it is useless on mobile devices

what i miss thanks in advance



  
    
    
    
  
  

I use SimpleHTTPServer for testing over LAN. When testing mobile devices, iOS and iPadOS only run on Safari