The problem is that the link color is not styled by the code entered into the style.css but rather in the same color as all other links, which is determined by the template itself (normalize.css), I guess. I have not changed the default CSS, by the way.
We are able to change the color of links in the normalize.css, but that would mean the same color for all links, whereas we prefer a different color for our rss-feed links.
Thanks for the quick help, it worked!
The only problem remaining is that the text itself remains in a color determined by the normalize.css and not in the style.css it seems. Do you have an idea how to change that without changing the color of all headers or links in the normalize.css to that same color?
In order to see what I mean, take a look at the page:
http://blog.ufz.de/watersciencealliance/