/* Ripple magic */
.btn-cf{
  cursor:pointer;
  position: relative;
  overflow: hidden;
}

.btn-cf:after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 5px;
  height: 5px;
  background: rgba(29, 127, 187, .5);
  opacity: 0;
  border-radius: 100%;
  transform: scale(1, 1) translate(-50%);
  transform-origin: 50% 50%;
}

@keyframes ripple {
  0% {
    transform: scale(0, 0);
    opacity: .5;
  }
  20% {
    transform: scale(50, 50);
    opacity: .8;
  }
  100% {
    opacity: 0;
    transform: scale(90, 90);
  }
}

.btn-cf:focus:not(:active)::after {
  animation: ripple 1s ease-out;
}