The default class for the <form> tag is “fm-form”, and the ID is based on the ID # (not the slug) for the form.  If your form’s ID # is ‘1’, then the <form> tag’s id will be ‘fm-form-1’.

If the ‘show border’ option is selected, the next tag after <form> is a fieldset, with no class selected.

The list of form items is within a <ul>, where each <li> has the class “fm-item-(nickname)” if the item has a nickname.  If the item does not have a nickname, the item’s unique identifier is used.  This will be the type of item (‘text’, ‘textarea’, etc.) followed by eight letters and numbers.

The submit button has the class “submit”.