.loader {
  --color-1: #FF0000;
  --color-2: #000000;
  --size: 0.4px;

  width: calc(48 * var(--size));
  height: calc(48 * var(--size));
  border-radius: 50%;
  display: inline-block;
  position: relative;
  border: calc(2 * var(--size)) solid var(--color-1);
  box-sizing: border-box;
  animation: rotation 1s linear infinite;
  left: 10px;
}
.loader::after {
  content: '';
  box-sizing: border-box;
  position: absolute;
  left: calc(4 * var(--size));
  top: calc(4 * var(--size));
  border: calc(2 * var(--size)) solid var(--color-2);
  width: calc(12 * var(--size));
  height: calc(12 * var(--size));
  border-radius: 50%;
}

@keyframes rotation {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}