.spinner-border {
    display: inline-block;
    width: 4rem;
    height: 4rem;
    vertical-align: text-bottom;
    border: .25em solid currentColor;
    border-right-color: transparent;
    border-radius: 50%;
    -webkit-animation: spinner-border .75s linear infinite;
    animation: spinner-border .75s linear infinite;
}

@keyframes spinner-border {
    to { transform: rotate(360deg); }
}