body {
  margin: 0;
}

.myBtn {
  width: 70px;
}

#preloader {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 9999;
  overflow: hidden;
  background: #fff;
}
#preloader:before {
  content: '';
  position: fixed;
  top: calc(50% - 30px);
  left: calc(50% - 30px);
  border: 6px solid #f2f2f2;
  border-top-color: #56829e;
  border-radius: 50%;
  width: 60px;
  height: 60px;
  -webkit-animation: animate-preloader 1s linear infinite;
  animation: animate-preloader 1s linear infinite;
}
@-webkit-keyframes animate-preloader {
  0% {
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }
  to {
    -webkit-transform: rotate(1turn);
    transform: rotate(1turn);
  }
}
@keyframes animate-preloader {
  0% {
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }
  to {
    -webkit-transform: rotate(1turn);
    transform: rotate(1turn);
  }
}