#scrollTopBtn {
  position: fixed;
  bottom: 30px;
  right: 35px;
  width: 80px;
  height: 80px;
  z-index: 9999;
  cursor: pointer;
}

#scrollTopBtn img {
  width: 100%;
  height: auto;
}

@media screen and (max-width: 767px) {
  #scrollTopBtn {
    bottom: 25px;
    right: 0;
  }

  #scrollTopBtn img {
    width: 70%;
  }
}