/* Absolute Center Spinner */
.loading {
    position: fixed;
    z-index: 999;
    height: 2em;
    width: 2em;
    overflow: visible;
    margin: auto;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;

    &:before {
        content: '';
        display: block;
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-color: rgba(0,0,0,0.3);
    }

    &:not(:required) {
        /* hide "loading..." text */
        font: 0/0 a;
        color: transparent;
        text-shadow: none;
        background-color: transparent;
        border: 0;

        &:after {
            content: '';
            display: block;
            font-size: 10px;
            width: 1em;
            height: 1em;
            margin-top: -0.5em;
            animation: spinner 1500ms infinite linear;
            border-radius: 0.5em;
            box-shadow: rgba(0, 0, 0, 0.75) 1.5em 0 0 0, rgba(0, 0, 0, 0.75) 1.1em 1.1em 0 0, rgba(0, 0, 0, 0.75) 0 1.5em 0 0, rgba(0, 0, 0, 0.75) -1.1em 1.1em 0 0, rgba(0, 0, 0, 0.75) -1.5em 0 0 0, rgba(0, 0, 0, 0.75) -1.1em -1.1em 0 0, rgba(0, 0, 0, 0.75) 0 -1.5em 0 0, rgba(0, 0, 0, 0.75) 1.1em -1.1em 0 0;
        }
    }
}


/* Animation */
@-webkit-keyframes spinner {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}
@-moz-keyframes spinner {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}
@-o-keyframes spinner {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}
@keyframes spinner {
    0% {
        transform: rotate(0deg);
    }
    100% {
        transform: rotate(360deg);
    }
}