@media screen and (max-height: 700px) {
  .wrap .lesson_border .playground_wrap {
    background: none;
  }
}

@media screen and (max-width:766px) , screen and (max-height:600px) {
  .wrap.desktop {
    display:none;
  }
  #mobile_welcome {
    display:block;
    margin-top:33%;
  }
}