Magento 2 add class to body via Layout Update XML

[x_falkone_x]

How I can add class to a body tag for CMS page via Layout Update XML. I am trying different variants like this

<referenceContainer name="root">
  <attribute name="class" value="my-css-class"/>
</referenceContainer>

But nothing works.

[ShoaibRehman89]

@x_falkone_x

Have you tried using htmlClass="new-class" ? 

<referenceContainer name="my.container" htmlClass="new-class" />

For further details: https://devdocs.magento.com/guides/v2.0/frontend-dev-guide/layouts/xml-manage.html 

Please accept my answer as Solution if I was able to help.