md/public/assets/css/loading.css

.loading {
    text-align: center;
    position: fixed;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: 99999;
    background-color: #f2f2f2;
}

.loading_night {
    background-color: #303133;
}

.loading-wrapper {
    position: fixed;
    top: 50%;
    left: 50%;
    -webkit-transform: translateX(-50%) translateY(-50%);
    -moz-transform: translateX(-50%) translateY(-50%);
    -ms-transform: translateX(-50%) translateY(-50%);
    transform: translateX(-50%) translateY(-50%);
}

.loading-text {
    line-height: 1.4;
    font-size: 1.2rem;
    font-weight: bold;
    margin-bottom: 1rem;
}

.loading-anim {
    width: 35px;
    height: 35px;
    border: 5px solid rgba(189, 189, 189, 0.25);
    border-left-color: rgba(66, 185, 131, 0.9);
    border-top-color: rgba(66, 185, 131, 0.9);
    border-radius: 50%;
    display: inline-block;
    animation: rotate 600ms infinite linear;
}

@keyframes rotate {
    to {
        transform: rotate(1turn)
    }
}