.modal-backdrop {
    --bs-backdrop-zindex: 1050;
    --bs-backdrop-bg: #000;
    --bs-backdrop-opacity: .5;
    position: fixed;
    top: 0;
    left: 0;
    z-index: var(--bs-backdrop-zindex);
    width: 100vw;
    height: 100vh;
    background-color: var(--bs-backdrop-bg)
}

.modal-backdrop.fade {
    opacity: 0
}

.modal-backdrop.show {
    opacity: var(--bs-backdrop-opacity)
}