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