vitalik1921

Before using you should open Settings -> Marketo Forms and enter your base URL and Subscriber ID. This information you 
can get from Marketo, or you can extract it from generated code in Marketo back-end. It looks like this:
MktoForms2.loadForm(“base url”, “subscriber id”, $form_id, callback_function);
After that you can use shortcode to display Marketo from:
[marketo id=10]
where id – is form identificator
Also developers can use function to display forms:
marketo_display_form($form_id);

Marketo Forms

Plugin allows to add Marketo forms (www.marketo.com) to the site using shortcodes and function. Also it makes forms responsive, and resets styles.

rodhomor

Remove the two CSS files, inline styles and unneeded, bloated HTML code when you embed Marketo forms into your site pages/posts.

Remove Marketo Form Styles

This plugin removes all inline styles, forced style sheets, and bloated HTML from your embedded Marketo forms.

Marketo Forms vs Remove Marketo Form Styles