Custom Class for Modular Pages

Is it possible to assign a custom class to a modular page? I know I can add body classes to the parent page but cannot seem to be able to add a custom CSS Class for the child modular pages.
I tried adding class:myclass to the frontmatter and in the md file but it is not recognized.

Thank you.

I am not sure if there is a built in way to do this but I just modified the twig template to allow the modular template to use body class for the modular-row.

I am testing with bootstrap and adding bootstrap classes to set width and position of the modular pages.