paperless-ngx/src-ui/src/app/components/common/custom-fields-dropdown/custom-fields-dropdown.component.scss

.custom-fields-dropdown {
    min-width: 300px;

    // correct position on mobile
    @media (max-width: 575.98px) {
        &.show {
            margin-left: -245px !important;
        }
    }
}