$d: 80vmin;
$line: linear-gradient(90deg, #be4c39 50%, transparent 0)
      0/ 2em .25em repeat-x;

body {
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  height: 100vh;
  background: lightslategray;
}

.☯ {
  display: flex;
  align-items: center;
  width: $d; height: $d;
  border-radius: 50%;
  background: $line, 
    linear-gradient(black 50%, white 0);
  
  &:before, &:after {
    flex: 1;
    border: solid $d/6 transparent;
    height: $d/6;
    border-radius: 50%;
    background: $line, 
      linear-gradient(black, black) content-box, 
      linear-gradient(white, white) border-box;
    animation: a1 3s ease-in-out infinite;
    content: ''
  }
  
  &:after {
    background: $line, 
      linear-gradient(white, white) content-box, 
      linear-gradient(black, black) border-box;
    animation-name: a2;
  }
}

@keyframes a1 {
  0% { transform: translatex(-50vw) }
  40%, 100% { transform: translatex(0) }
}

@keyframes a2{
  0%, 40% { transform: translatex(50vw) }
  80%, 100% { transform: translatex(0) }
}