.loader {
    width: 50px;
    aspect-ratio: 1;
    border-radius: 50%;
    margin: auto;
    border: 8px solid;
    border-color: #000 #0000;
    animation: l1 1s infinite;
    position: relative;
    align-items: center;
    margin: 20px auto;
}

.loader::before {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: inherit;
    background-color: #0000;
    animation: l2 1s infinite;
}

@keyframes l1 {to{transform: rotate(.5turn)}}