.body{
	overflow: hidden;
}
.main{
	width: 100%;
	display: block;
	position: relative;
}
.main img.fv{
	width: 100%;
	height: auto;
	margin: 0 auto;
	display: block;
}
.btn{
	position: absolute;
	width: 90%;
	display: block;
	left: calc((100% - 90%) / 2);
	bottom: 35px;
}
.btn img{
	width: 100%;
}
@media screen and (min-width: 768px) {
	.main{
		width: 640px;
		display: block;
		position: relative;
		margin: auto;
	}
	.btn{
		position: absolute;
		width: 563px;
		display: block;
		left: calc((100% - 563px) / 2);
		bottom: 67px;
	}
}
@keyframes floatBtn {
  0% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-12px);
  }
  100% {
    transform: translateY(0);
  }
}

img[src*="btn.png"] {
  animation: floatBtn 2s ease-in-out infinite;
}