.loader {
  width: fit-content;
  font-weight: bold;
  font-family: monospace;
  font-size: 30px;
  background: radial-gradient(circle closest-side,#000 94%,#0000) right/calc(200% - 1em) 100%;
  animation: l24 1s infinite alternate linear;
}

.loader::before {
  content: "Loading...";
  line-height: 1em;
  color: #0000;
  background: inherit;
  background-image: radial-gradient(circle closest-side,#fff 94%,#000);
  -webkit-background-clip:text;
          background-clip:text;
}

@keyframes l24{
  100%{background-position: left}
}