MktoForms2.lightbox(form).show(); is Marketo Forms lightbox code.
"Modal" and "lightbox" are the same thing. The Marketo lightbox, for example, uses the class "mktoModal," illustrating the equivalence of the two concepts. There is no such thing as a cross-browser modal window, actually -- except for a native alert popup -- so you're always using a 3rd-party library. In your code, you're using the Marketo library, as I am in my demo.
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