Section will be overlapped by header when come from another page

I have the following problem. What I want is when the user clicks in the navigation bar on "Contact" it will link to the contact page. This is a single page. When you are on contact and then clicking at the bottom of the page on, for example "Over ons" it should be redirect to the homepage (single page) and stop at that section. This works, but when you come from another page, the current section is overlapped by the header.

The jQuery code will not use the offset of the header, only when you are navigation inside the index.html.

Is there a way to fix the issue, so the section will not be overlapped by the header?

Live example:

http://ift.tt/1KRmFou