SOURCE

<div class="loader">
    <svg class="circular" viewBox="25 25 50 50">
        <circle class="path" cx="50" cy="50" r="20" fill="none" stroke-width="3"
        stroke-miterlimit="10">
        </circle>
    </svg>
</div>

.loader {
    position: relative;
    top: 100px;
    margin: 0 auto;
    width: 50px;
}

.loader:before {
    content: '';
    display: block;
    padding-top: 100%;
}

.circular {
    animation: rotate 2s linear infinite;
    height: 100%;
    transform-origin: center center;
    width: 100%;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
}

.path {
    stroke-dasharray: 1, 200;
    stroke-dashoffset: 0;
    animation: dash 1.5s ease-in-out infinite, color 6s ease-in-out infinite;
    stroke-linecap: round;
}

.ani_opa,
.ani_opa_hide {
    -webkit-animation-duration: .2s;
    -webkit-animation-timing-function: ease-in-out;
    -webkit-animation-fill-mode: both;
}

@keyframes rotate {
    100% {
        transform: rotate(360deg);
    }
}

@keyframes dash {
    0% {
        stroke-dasharray: 1, 200;
        stroke-dashoffset: 0;
    }
    50% {
        stroke-dasharray: 89, 200;
        stroke-dashoffset: -35;
    }
    100% {
        stroke-dasharray: 89, 200;
        stroke-dashoffset: -124;
    }
}

@keyframes color {
    0%,
    100% {
        stroke: #d62d20;
    }
    40% {
        stroke: #0057e7;
    }
    66% {
        stroke: #008744;
    }
    80%,
    90% {
        stroke: #ffa700;
    }
}