/* HTML: <div class="loader"></div> */
.loader {
    margin: 0 auto;
    width: 100px;
    height: 40px;
    color: #000;
    border: 2px solid currentColor;
    border-right-color: transparent;
    padding: 3px;
    background:
            repeating-linear-gradient(90deg,currentColor 0 10px,#0000 0 15px)
            0/0% no-repeat content-box content-box;
    position: relative;
    box-sizing: border-box;
    animation: l5 2s infinite steps(6);
}
.loader::before {
    content: "";
    position: absolute;
    top: -2px;
    bottom: -2px;
    left: 100%;
    width: 10px;
    background:
            linear-gradient(
                    #0000   calc(50% - 7px),currentColor 0 calc(50% - 5px),
                    #0000 0 calc(50% + 5px),currentColor 0 calc(50% + 7px),#0000 0) left /100% 100%,
            linear-gradient(currentColor calc(50% - 5px),#0000        0 calc(50% + 5px),currentColor 0) left /2px 100%,
            linear-gradient(#0000        calc(50% - 5px),currentColor 0 calc(50% + 5px),#0000        0) right/2px 100%;
    background-repeat:no-repeat;
}
@keyframes l5 {
    100% {background-size:120%}
}