.loader {
  position: absolute;
  top:0;
  bottom: 0;
  left: 0;
  right: 0;
  margin: auto;
  width: 100px;
  height: 100px;
  aspect-ratio: 1;
  border-radius: 50%;
  border: 8px solid;
  border-color: #000 #0000;
  animation: l1 1s infinite;
}

@keyframes l1 {
    to
    {
        transform: rotate(.5turn)
        
    }
    0%
    {
        opacity: 0;
    }
    50%
    {
        opacity: 1;
    }
    100%
    {
        opacity: 0;
    }
}