.box_help {
  transition: ease 300ms;
}

.box_help:hover {
  margin-top: -2.5%;
}

#desc.block {
  transition: ease-in-out 2ms;
  animation-name: shwo;
  animation-duration: 2s;
}

#desc.hidden {
  transition: ease-in-out 2ms;
  animation-name: hideblock;
  animation-duration: 2s;
}

@keyframes shwo {
  0% {
    opacity: 0;
  }

  50% {
    opacity: 50;
  }

  100% {
    opacity: 100;
  }
}

@keyframes hideblock {
  0% {
    opacity: 100;
  }

  50% {
    opacity: 50;
  }

  100% {
    opacity: 0;
  }
}