message: Make the empty pane menu shrink when needed
diff: --empty-pane-menu-container-width: 400px;
  display: block;
  - width: var(--empty-pane-menu-container-width);
  - margin-left: calc((100% - var(--empty-pane-menu-container-width) )/2);
  - margin-right: calc((100% - var(--empty-pane-menu-container-width) )/2);
  + width: 100%;
  + max-width: var(--empty-pane-menu-container-width);
  +
  + margin-left: auto;
  + margin-right: auto;
  }
  #ID_TITLE {
  