Change the color of the Featured Pages Buttons

Hello,

The snippet “Change the color of the Featured Pages Buttons” doens not work for me. I put all the code in the child style.css and in the function.php. Dave thought that there must be some other css code with higher ‘specificity’ which is overriding this css.
I removed all the other css frome the style.css and the buttons did not change from color.
Take a look at http://www.durksweb.nl/website3.

Is there anyone who has the same problem and knows how to fix it?