*{box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    height: 100vh;
    width: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
}


/* HTML: <div class="loader"></div> */
.loader {
  width: 50px;
  padding: 8px;
  aspect-ratio: 1;
  border-radius: 50%;
  background: #25b09b;
  --_m:
    conic-gradient(#0000 10%,#000),
    linear-gradient(#000 0 0) content-box;
  -webkit-mask: var(--_m);
          mask: var(--_m);
  -webkit-mask-composite: source-out;
          mask-composite: subtract;
  animation: l3 1s infinite linear;
}
@keyframes l3 {to{transform: rotate(1turn)}}