.spinner-border {
    display: inline-block;
    width: 2rem;
    height: 2rem;
    vertical-align: text-bottom;
    border: 0.25em solid currentColor;
    border-right-color: transparent;
    border-radius: 50%;
    -webkit-animation: spin .75s linear infinite;
    animation: spin .75s linear infinite;
}
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    overflow: hidden;
    clip: rect(0,0,0,0);
    white-space: nowrap;
    border: 0;
}

@-moz-keyframes spin {
    100% { -moz-transform: rotate(360deg); }
}
@-webkit-keyframes spin {
    100% { -webkit-transform: rotate(360deg); }
}
@keyframes spin {
    100% {
        -webkit-transform: rotate(360deg);
        transform:rotate(360deg);
    }
}