javascript - display: none doesn't work -

i have web app making music javascript. have problem display: none of .musicbox class.

here index.html code important styles & scripts.

my index.html file on codepen

  @media screen , (max-width: 520px) {       .rotatedevice {           display: block;        }       .tonebox {           display: none;       }   } 

when resize window under 520px width 'display: none' color boxes. why didn't?

there missing above media query.

remove .a above it.