Ghost/ghost/admin/app/styles/components/loading-indicator.css

/* Loading state */
.gh-loading-content {
    display: flex;
    flex-direction: row;
    align-items: center;
    overflow: hidden;
    top: 0;
    bottom: 0;
    position: absolute;
    width: 100%;
    justify-content: center;
    left: 0;
    padding-bottom: 8vh;
}

.gh-loading-content.basic-auth {
    z-index: 1000;
}

.gh-loading-spinner {
    position: relative;
    display: inline-block;
    box-sizing: border-box;
    margin: -2px 0;
    width: 50px;
    height: 50px;
    border: rgba(0,0,0,0.1) solid 1px;
    border-radius: 100px;
    animation: spin 1s linear infinite;
}

.gh-loading-spinner:before {
    content: "";
    display: block;
    margin-top: 7px;
    width: 7px;
    height: 7px;
    background: #4C5156;
    border-radius: 100px;
    z-index: 10;
}

@keyframes spin {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

/* Infinite scroll */
.infinity-loader {
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: center;
    padding: 2em 0;
}