Linkcolor is white

All links we create are colored in white even though I set them to another color (in this case black, but I have tried other colors) in the Style Editor.

Here is an example:
After this text there is a link to an internal page: Link to Frontpage
After this text there is a link to google.com: Link to google

When editing a page the links are displayed in the right color (see screenshot below).

When you click on save, select another page in the "squarespace page-menu" and then select the original page with the links, they are invisible because of the white text on white background.
However, most importantly this is also the case when viewing the page outside of squarespace:

 

This even happens with automatically generated links, like in the summary block below.