.loader {
   --color-1: #343168;
   --size: 0.7px;

   width: calc(32 * var(--size));
   height: calc(32 * var(--size));
   position: relative;
   border-radius: 50%;
   color: var(--color-1);
   animation: fill 1s ease-in infinite alternate;
 }

 .loader::before,
 .loader::after {
   content: '';
   position: absolute;
   height: 100%;
   width: 100%;
   border-radius: 50%;
   left: calc(48 * var(--size));
   top: 0;
   animation: fill 0.9s ease-in infinite alternate;
 }

 .loader::after {
   left: auto;
   right: calc(48 * var(--size));
   animation-duration: 1.1s;
 }

 @keyframes fill {
   0% {
     box-shadow: 0 0 0 calc(2 * var(--size)) inset;
   }

   100% {
     box-shadow: 0 0 0 calc(10 * var(--size)) inset;
   }
 }