Material Design Spinner (https://codepen.io/mrrocks/pen/EiplA)

spinner.html

<svg class="spinner" width="65px" height="65px" viewBox="0 0 66 66" xmlns="http://www.w3.org/2000/svg">
   <circle class="path" fill="none" stroke-width="6" stroke-linecap="round" cx="33" cy="33" r="30"></circle>
</svg>

<style>
   // This is just to center the spinner

html, body { height: 100%; }

body {
   display: flex;
   align-items: center;
   justify-content: center;
}

// Here is where the magic happens

$offset: 187;
$duration: 1.4s;

.spinner {
  animation: rotator $duration linear infinite;
}

@keyframes rotator {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(270deg); }
}

.path {
  stroke-dasharray: $offset;
  stroke-dashoffset: 0;
  transform-origin: center;
  animation:
    dash $duration ease-in-out infinite, 
    colors ($duration*4) ease-in-out infinite;
}

@keyframes colors {
	0% { stroke: #4285F4; }
	25% { stroke: #DE3E35; }
	50% { stroke: #F7C223; }
	75% { stroke: #1B9A59; }
  100% { stroke: #4285F4; }
}

@keyframes dash {
 0% { stroke-dashoffset: $offset; }
 50% {
   stroke-dashoffset: $offset/4;
   transform:rotate(135deg);
 }
 100% {
   stroke-dashoffset: $offset;
   transform:rotate(450deg);
 }
}
</style>