Great circular SVG material design spinner. Original: http://david.ingledow.co.uk/blog/google-material-designs-animated-loading-spinner-svg-and-css/

index.html

<div class="loader">
  <svg class="circular" viewBox="25 25 50 50">
    <circle class="path" cx="50" cy="50" r="20" fill="none" stroke-width="2" stroke-miterlimit="10"/>
  </svg>
</div>

spinner.scss

$green: #eee;
$blue: #eee;
$red: #eee;
$yellow: #eee;
$white: #eee;

$width: 11.9vh;

.loader {
  position: absolute;
  width: $width;
  height: $width;

  display: none;
}

.circular{
  animation: rotate 2s linear infinite;
  height: $width;
  position: relative;
  width: $width;
}


.path {
  stroke-dasharray: 1,200;
  stroke-dashoffset: 0;
  animation:
          dash 1.5s ease-in-out infinite,
          color 6s ease-in-out infinite
;
  stroke-linecap: round;
}

@keyframes rotate{
  100%{
    transform: rotate(360deg);
  }
}
@keyframes dash{
  0%{
    stroke-dasharray: 1,200;
    stroke-dashoffset: 0;
  }
  50%{
    stroke-dasharray: 89,200;
    stroke-dashoffset: -35;
  }
  100%{
    stroke-dasharray: 89,200;
    stroke-dashoffset: -124;
  }
}
@keyframes color{
  100%, 0%{
    stroke: $red;
  }
  40%{
    stroke: $blue;
  }
  66%{
    stroke: $green;
  }
  80%, 90%{
    stroke: $yellow;
  }
}