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

.spinner-border {
    position: relative;
    display: inline-block;
    width: 2rem;
    height: 2rem;
    overflow: hidden;
    text-indent: -999em;
    vertical-align: text-bottom;
    border: .25em solid;
    border-color: currentColor transparent currentColor currentColor;
    border-radius: 50%;
    animation-name: spinner-border;
    animation-duration: .75s;
    animation-timing-function: linear;
    animation-iteration-count: infinite;
}

.spinner-border-reverse {
    border-color: transparent currentColor transparent transparent;

    &::after {
         position: absolute;
         top: -.25em;
         right: -.25em;
         bottom: -.25em;
         left: -.25em;
         display: inline-block;
         content: "";
         border: .25em solid rgba(0, 0, 0, .1);
         border-radius: 50%;
     }
}

.spinner-border-sm {
    width: 1rem;
    height: 1rem;
    border-width: .2em;

    &.spinner-border-reverse::after {
         border-width: .2em;
     }
}
@keyframes spinner-grow {
    0% {
        opacity: 0;
        transform: scale(0);
    }
    50% {
        opacity: 1;
    }
    100% {
        opacity: 0;
        transform: scale(1);
    }
}

.spinner-grow {
    position: relative;
    display: inline-block;
    width: 2rem;
    height: 2rem;
    overflow: hidden;
    text-indent: -999em;
    vertical-align: text-bottom;
    background-color: currentColor;
    border-radius: 50%;
    animation-name: spinner-grow;
    animation-duration: .75s;
    animation-timing-function: linear;
    animation-iteration-count: infinite;
}

.spinner-grow-sm {
    width: 1rem;
    height: 1rem;
}

.box .overlay,
.overlay-wrapper > .overlay,
.box > .loading-img,
.overlay-wrapper > .loading-img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}
.box .overlay,
.overlay-wrapper .overlay {
    z-index: 50;
    background: rgba(255, 255, 255, 0.3);
    border-radius: 3px;
}
.box .overlay > .spinner-border, .box .spinner-border,
.overlay-wrapper .overlay > .spinner-grow, .box .spinner-border {
    position: absolute;
    top: 50%;
    left: 50%;
    margin-left: -10px;
    margin-top: -10px;
    color: #000;
    font-size: 20px;
}
.box .overlay.dark,
.overlay-wrapper .overlay.dark {
    background: rgba(0, 0, 0, 0.5);
}