/* HTML: <div class="loader"></div> */
.loader {
    width: 120px;
    height: 20px;
    -webkit-mask: linear-gradient(90deg,#000 70%,#0000 0) left/20% 100%;
    background:
            linear-gradient(#000 0 0) left -25% top 0 /20% 100% no-repeat
            #ddd;
    animation: l7 1s infinite steps(6);
}
@keyframes l7 {
    100% {background-position: right -25% top 0}
}