Page scrolls to bottom on close

when closing a modal popup by either the x or clicking off the popup the page scrolls to the bottom. on long pages this is annoying.

The problem occurs in FF33 and IE

I have attempted to implement the fix suggested here
http://stackoverflow.com/questions/12213267/colorbox-stop-background-scroll-and-return-to-same-location-on-parent-page

unfortunately it does not work

a similar problem is discussed here
https://wordpress.org/support/topic/closing-modal-jumps-page-to-bottom?replies=18

This is the site having the problem
http://yourterms.com.au

https://wordpress.org/plugins/form-lightbox/