.loader {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    display: block;
    margin: 15px auto;
    position: relative;
    color: #FFF;
    left: -100px;
    box-sizing: border-box;
    animation: shadowRolling 2s linear infinite;
}

@keyframes shadowRolling {
    0% {
        box-shadow: 0px 0 rgba(255, 255, 255, 0), 0px 0 rgba(255, 255, 255, 0), 0px 0 rgba(255, 255, 255, 0), 0px 0 rgba(255, 255, 255, 0);
    }

    12% {
        box-shadow: 100px 0 black, 0px 0 rgba(255, 255, 255, 0), 0px 0 rgba(255, 255, 255, 0), 0px 0 rgba(255, 255, 255, 0);
    }

    25% {
        box-shadow: 110px 0 black, 100px 0 black, 0px 0 rgba(255, 255, 255, 0), 0px 0 rgba(255, 255, 255, 0);
    }

    36% {
        box-shadow: 120px 0 black, 110px 0 black, 100px 0 black, 0px 0 rgba(255, 255, 255, 0);
    }

    50% {
        box-shadow: 130px 0 black, 120px 0 black, 110px 0 black, 100px 0 black;
    }

    62% {
        box-shadow: 200px 0 rgba(255, 255, 255, 0), 130px 0 black, 120px 0 black, 110px 0 black;
    }

    75% {
        box-shadow: 200px 0 rgba(255, 255, 255, 0), 200px 0 rgba(255, 255, 255, 0), 130px 0 black, 120px 0 black;
    }

    87% {
        box-shadow: 200px 0 rgba(255, 255, 255, 0), 200px 0 rgba(255, 255, 255, 0), 200px 0 rgba(255, 255, 255, 0), 130px 0 black;
    }

    100% {
        box-shadow: 200px 0 rgba(255, 255, 255, 0), 200px 0 rgba(255, 255, 255, 0), 200px 0 rgba(255, 255, 255, 0), 200px 0 rgba(255, 255, 255, 0);
    }
}