.main-content {
    background: url('../images/background.png') no-repeat center center/cover;
}

.main-content::before {
    content: '';
    background: url('../images/overlay.png') no-repeat center center;
    background-size: contain;
    width: 80%;
    height: 80%;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 1;
}