:root { --animation-mainstage-id: 'fade-in'; }

/* mainstages fade-in */
@keyframes anim-fade-in {
    0% {
        opacity: 0
    }

    to {
        opacity: 1
    }
}

.mstg [class*="mn_"] {
    animation: anim-fade-in 0.5s ease-out both;
}