http://www.ruimzicht.eu/index.php?page=contact
The button for validation is on the bottom-left, in the footer.
The message the validation gives back is:
How to have this validated?Error Line 177 column 122: document type does not allow element "form" here; missing one of "object", "applet", "map", "iframe", "ins", "del" start-tag.
Ronny