should we use it with CSS or direct right it with form messageML format, An example to implement these style attribute would be very helpful.

It would be advised to review the documentation link provided then try to formulate the MessageML in the PresentationML Renderer Tool to test to see whether the MessageML will render in Symphony.

As mentioned - there is similarities but not a direct like for like to other markup languages - meaning there will be small differences to the style formatting but you can take a look at the 'Sample' template from the PresentationML Renderer Tool to see what can be achieved.

Hope that helps.