Hi Stine, if I’m not mistaken we already had email contact about this but for anyone viewing this thread, searching for a similar answer:
Both in the widget and the coolclock shortcode it is possible to switch to a Custom skin. But even if you need only one element’s color changed, you’ll still need to define most other elements or the custom skin will not function well.
Visit https://premium.status301.net/coolclock-skins/ and copy the parameter code beside your favorite clock. Then read further on how to apply and adapt your own clock skin for both the widget and shortcode.