Generated by SassMeister.com.

SassMeister-input-HTML.html

<span class="spinner"></span>

SassMeister-input.scss

// ----
// Sass (v3.4.6)
// Compass (v1.0.1)
// ----

@import "compass";

@include keyframes(spin) {
  to { transform: rotate(1turn); }
}

.spinner {
  @include animation(spin 1s infinite);
  border: .375rem double black;
  border-radius: 100%;
  border-top-style: solid;
  display: inline-block;
  height: 1rem;
  width: 1rem;
}

SassMeister-output.css

@-moz-keyframes spin {
  to {
    transform: rotate(1turn);
  }
}
@-webkit-keyframes spin {
  to {
    transform: rotate(1turn);
  }
}
@keyframes spin {
  to {
    transform: rotate(1turn);
  }
}
.spinner {
  -moz-animation: spin 1s infinite;
  -webkit-animation: spin 1s infinite;
  animation: spin 1s infinite;
  border: .375rem double black;
  border-radius: 100%;
  border-top-style: solid;
  display: inline-block;
  height: 1rem;
  width: 1rem;
}

SassMeister-rendered.html

<span class="spinner"></span>