details.details_shim_closed, details.details_shim_open {
  display: block
}

  details.details_shim_closed > * {
    display: none
  }

  details.details_shim_closed > summary, details.details_shim_open > summary {
    display: block
  }

    details.details_shim_closed > summary:before {
      display: inline-block;
      content: "\25b6";
      padding: 0 .1em;
      margin-right: .4em;
      font-size: .9em
    }

    details.details_shim_open > summary:before {
      display: inline-block;
      content: "\25bc";
      padding: 0;
      margin-right: .35em
    }