iFrame, header image disappears?

Hello,

I have embedded my form via iFrame, onto my squarespace site. It all looks fine, except the header of my form appears for a second upon loading, and then disappears (see here: http://affluentappraisals.com/quick-valuation-form)

How do I fix this?  The space where the header should be seems much larger than my actual header - and it is also make part of the form itself (not the header) disappear.

Does anyone know what I am doing wrong?

Please help.

Phoebe

It worked perfectly! Thanks so much!