@keyframes obracanko {
    0% {transform: scale(1.0, 1.0);}
    25% {transform: scale(0.0, 1.0);}
    50% {transform: scale(-1.0, 1.0);}
    75% {transform: scale(0.0, 1.0);}
    100% {transform: scale(1.0, 1.0);}
}

#obr {
    position: absolute;
    width: 70vw;
    height: 53vh;
    left: 0;
    right: 0;
    margin-inline: auto;
    top: 20%;
    animation: obracanko 4s ease-in-out alternate infinite;
    box-shadow: 0px 10px 7px -2px rgba(0, 0, 0, 0.25);
}