<container name="page.wrapper" as="page_wrapper" htmlTag="div" htmlClass="page-wrapper">
            <block class="MagentoFrameworkViewElementTemplate" name="wrapper" template="Magento_Theme::html/wrapper.phtml">
                <container name="page.subwrapper" as="page_subwrapper" htmlTag="div" htmlClass="page-subwrapper">
                    ...
                </container>
            </block>
        </container>

<layout xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_layout.xsd">
    <update handle="empty"/>
    <referenceContainer name="page.subwrapper">
        ...
    </referenceContainer>
</layout>

<div class="customer-group">
    <?= $block->getChildHtml() ?>
</div>