t: 300px">
                        <p>Cool thing.</p>
                      </div>
                    </calcite-block-content>
                  </calcite-block>
                  <calcite-block collapsible open heading="Additional Block" summary="This is the primary.">
                    <calcite-block-content>
                      <div style="height: 300px">
                        <p>Cool thing.</p>
                      </div>
                    </calcite-block-content>
                  </calcite-b