wagtail/client/scss/layouts/_modeladmin-choose-parent-page.scss

// stylelint-disable-next-line selector-max-id
.modeladmin #id_parent_page li {
  margin: 15px 0;
}

// stylelint-disable-next-line selector-max-id
.modeladmin #id_parent_page li label {
  float: none;
}