How to add a new container to a layout (extending Magento Blank)
You need to have at least one child block with output in order to have the container rendered.
Example:
<container name="mike.container" as="mikeContainer" label="Mike Container" htmlTag="div" htmlClass="mike-container">
<block class="Magento\Framework\View\Element\Text" name="testtextblock">
<arguments>
<argument name="text" xsi:type="string"><![CDATA[<!-- -->]]></argument>
</arguments>
</block>
</container>
