.loader {
    display: block;
    position: absolute;
    width: 50px;
    height: 50px;
    left: calc(50% - 25px);
    top: calc(50% - 25px);
    text-align: center;

    animation-name: rotate;
    animation-duration: 2s;
    animation-iteration-count: infinite;
    animation-timing-function: linear;
}

.loader::after {
    content: '⌛';
    display: inline-block;
    font-size: 40px;
    vertical-align: middle;
}

@keyframes rotate {
    from {
        transform: rotate(0deg);
    }

    to {
        transform: rotate(360deg);
    }
}