/* pc */
@media screen and (min-width: 769px) {
  #myBtn {
	  padding: 10px 20px;
	  font-size: 2vw;
	  bottom: 8%; 
  }
}
/* tablet  */
@media only screen and (min-width: 641px) and (max-width: 960px) {
  #myBtn {
	  padding: 9.5px;
	  font-size: 3vw;
	  bottom: 4%; 
  }
}
/* smartPhone */
@media screen and (max-width: 641px) {
  #myBtn {
	  padding: 9.5px;
	  font-size: 4vw;
	  bottom: 2.5%;
  }
}

#myBtn {
  display: none; /* Hidden by default */
  position: fixed; /* Fixed/sticky position */
  /* Place the button at the bottom of the page */
  right: 3%; /* Place the button 30px from the right */
  z-index: 99; /* Make sure it does not overlap */
  border: none; /* Remove borders */
  outline: none; /* Remove outline */
  background-color: #535353; /* Set a background color */
  color: white; /* Text color */
  opacity: 50%;
  cursor: pointer; /* Add a mouse pointer on hover */
   /* Some padding */
  border-radius: 10px; /* Rounded corners */
   /* Increase font size */
}

#myBtn:hover {
  opacity: 100%;
}