.btn {
  color: #fff;
  padding: 10px 40px;
  background-color: #721B18;
  cursor: pointer;
  box-shadow: 0 7px #A02522;
  border-radius: 5px;
  font-size: 20px;
  display: inline-block;
  letter-spacing: 0.2em;
  text-decoration: none;
}

.btn:active {
  position: relative;
  top: 7px;
  box-shadow: none;
}

/*--- cssアニメーション ここから ---*/
.keyframe {
  animation-name: anim_sc;
  transform: scale(0.6, 0.6);
}

@keyframes anim_sc {
  100% {
    transform: scale(1, 1);
  }
}

.animation {
  animation-timing-function: ease-in-out;
  animation-iteration-count: infinite;
  animation-direction: alternate;
  animation-duration: 1.5s;
}

/*--- cssアニメーション ここまで ---*/