Apply margin to inner elements in a Yesod form

Question

I'm trying to apply margin to elements inside a renderDivs form:

    <$> areq textField (FieldSettings "Name: " 
                                      Nothing
                                      (Just "hs12")
                                      Nothing
                                      [("class","myClass")]
                       ) (fmap flavourName prod)
    <*> areq doubleField "Price: " (fmap flavourPrice prod)
    <*> areq textField "Description: " (fmap flavourDescription prod)

Is it possible?

Because I didn't understood how I can manipulate the CSS of form's inner elements with Yesod framework.

I am able to manipulate the <form> tag, but not its inner elements:

<form action=@{rt} method=post style="margin: 10px 0px 0px 5px">