accounts-frontend/src/components/ui/popup/popup.scss

.overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;

    z-index: 200;

    background: rgba(255, 255, 255, 0.8);

    text-align: center;
    white-space: nowrap;

    overflow-x: hidden;
    overflow-y: auto;

    &:before {
        content: '';
        display: inline-block;
        vertical-align: middle;
        height: 100%;
        width: 0;
    }
}

.popup {
    display: inline-block;
    white-space: normal;
    text-align: left;
    vertical-align: middle;

    width: 400px;
    max-width: 90%;

    background: #fff;
    padding: 30px;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.2);

    :invalid {
        button {
            opacity: 0.3;
            pointer-events: none;
        }
    }
}