jump to anchor link not working on smartphone

Hello,
I have two links in my navigation (“Portfolio” and “Kontakt”), where the site should jump to an anchor on another page. It works on most devices, but not in the way it should.

Klicking on Portfolio:
The site jumps almost to the right place, but the user has to scroll down a bit. I’d like the site to jump to the point that the colorsection starts exacly at the top border of the browser-window.

Klicking on Kontakt:
The site jumps to the right page and anchor, but the scrolls down too far (I tried to solve this by adding an additional color section with the right id above the actual section, but I’m not so happy witrh that)

On my iphone4 klicking on “Kontakt” makes the site jump to the right page, but it stops on the top of the page and doesn’t move to the anchor at all.

What can I do?
Thankyou!