html

<div class="loader"></div>

css

<style>
    body {
        background-color: #000;
    }

    .loader {
        position: relative;
        width: 2.5em;
        height: 2.5em;
        transform: rotate(165deg);
    }

    .loader:before,
    .loader:after {
        content: "";
        position: absolute;
        top: 50%;
        left: 50%;
        display: block;
        width: 0.5em;
        height: 0.5em;
        border-radius: 0.25em;
        transform: translate(-50%, -50%);
    }

    .loader:before {
        animation: before8 2s infinite;
    }

    .loader:after {
        animation: after6 2s infinite;
    }

    @keyframes before8 {
        0% {
            width: 0.5em;
            box-shadow: 1em -0.5em rgba(225, 20, 98, 0.75), -1em 0.5em rgba(111, 202, 220, 0.75);
        }

        35% {
            width: 2.5em;
            box-shadow: 0 -0.5em rgba(225, 20, 98, 0.75), 0 0.5em rgba(111, 202, 220, 0.75);
        }

        70% {
            width: 0.5em;
            box-shadow: -1em -0.5em rgba(225, 20, 98, 0.75), 1em 0.5em rgba(111, 202, 220, 0.75);
        }

        100% {
            box-shadow: 1em -0.5em rgba(225, 20, 98, 0.75), -1em 0.5em rgba(111, 202, 220, 0.75);
        }
    }

    @keyframes after6 {
        0% {
            height: 0.5em;
            box-shadow: 0.5em 1em rgba(61, 184, 143, 0.75), -0.5em -1em rgba(233, 169, 32, 0.75);
        }

        35% {
            height: 2.5em;
            box-shadow: 0.5em 0 rgba(61, 184, 143, 0.75), -0.5em 0 rgba(233, 169, 32, 0.75);
        }

        70% {
            height: 0.5em;
            box-shadow: 0.5em -1em rgba(61, 184, 143, 0.75), -0.5em 1em rgba(233, 169, 32, 0.75);
        }

        100% {
            box-shadow: 0.5em 1em rgba(61, 184, 143, 0.75), -0.5em -1em rgba(233, 169, 32, 0.75);
        }
    }

    .loader {
        position: absolute;
        top: calc(50% - 1.25em);
        left: calc(50% - 1.25em);
    }
</style>