.dots-7 {
  width: 60px;
  aspect-ratio: 4;
  --_g: no-repeat radial-gradient(circle closest-side,#167fff 90%,#0000);
  background: 
    var(--_g) 0%   50%,
    var(--_g) 50%  50%,
    var(--_g) 100% 50%;
  background-size: calc(100%/3) 100%;
  animation: d7 1s infinite linear;
}
@keyframes d7 {
    33%{background-size:calc(100%/3) 0%  ,calc(100%/3) 100%,calc(100%/3) 100%}
    50%{background-size:calc(100%/3) 100%,calc(100%/3) 0%  ,calc(100%/3) 100%}
    66%{background-size:calc(100%/3) 100%,calc(100%/3) 100%,calc(100%/3) 0%  }
}