Anchors not linking on header

I’ve had a look and it seems the issue is related to your theme. Your header section is absolutely positioned which means it actually overlays the buttons. It is transparent, so you can still see the button, but because the header is technically on top, you can’t click the links.

I think the easiest fix is to just make the button set in the header be absolutely positioned as well, so it will once again be on top.
You should be able to accomplish that with something like this added to the bottom of your theme’s styles.css file:

#gk-header > div.crafty-social-buttons.crafty-social-link-buttons {
position: absolute;
top: 0;
left: 0;
z-index: 1000;
}