.loader {
  border-radius: 50%;
  border-top: 16px rgba(0,0,0,0.75) solid;
  border-left: 16px rgba(0,0,0,0.25) solid;
  border-bottom: 16px rgba(0,0,0,0.25) solid;
  border-right: 16px rgba(0,0,0,0.25) solid;
  animation: spSlices 1s infinite linear;
}

@keyframes spSlices {
  0% {
    border-top: 16px rgba(0,0,0,0.75) solid;
    border-right: 16px rgba(0,0,0,0.25) solid;
    border-bottom: 16px rgba(0,0,0,0.25) solid;
    border-left: 16px rgba(0,0,0,0.25) solid;
  }

  25% {
    border-top: 16px rgba(0,0,0,0.25) solid;
    border-right: 16px rgba(0,0,0,0.75) solid;
    border-bottom: 16px rgba(0,0,0,0.25) solid;
    border-left: 16px rgba(0,0,0,0.25) solid;
  }

  50% {
    border-top: 16px rgba(0,0,0,0.25) solid;
    border-right: 16px rgba(0,0,0,0.25) solid;
    border-bottom: 16px rgba(0,0,0,0.75) solid;
    border-left: 16px rgba(0,0,0,0.25) solid;
  }

  75% {
    border-top: 16px rgba(0,0,0,0.25) solid;
    border-right: 16px rgba(0,0,0,0.25) solid;
    border-bottom: 16px rgba(0,0,0,0.25) solid;
    border-left: 16px rgba(0,0,0,0.75) solid;
  }

  100% {
    border-top: 16px rgba(0,0,0,0.75) solid;
    border-right: 16px rgba(0,0,0,0.25) solid;
    border-bottom: 16px rgba(0,0,0,0.25) solid;
    border-left: 16px rgba(0,0,0,0.25) solid;
  }
}