@media screen and (min-width: 1200px) {
  .edit-post-layout.is-sidebar-opened .edit-post-sidebar,
  .edit-post-layout.is-sidebar-opened .edit-post-plugin-sidebar__sidebar-layout {
    width: 600px;
  }

  .edit-post-layout.is-sidebar-opened .edit-post-layout__content {
    margin-right: 600px;
  }

  .wp-block {
    max-width: 1000px;
  }
}