Hello Bernhard,
Thanks for writing in! There is a JS error on the page. You may have inserted this in the Cornerstone Custom JS section:
//
// No need to add script tags
// here; simply get started
// by writing JavaScript!
// Remember to save your
// changes to see them :)
//
min-height: 500px; </script> <script>
jQuery(document).ready(function() {
});
I am not sure what is it for. Please remove it and then after making the site changes, always remember to clear all caches since you have installed WP SuperCache plugin so that the code from the latest changes is always in use. This will help you to avoid any potential errors.
And please clear your browser cache too. You may use private browsing mode in testing your site to make sure that you are viewing the latest codes from the updates and not the cached version in your browser.
Hope this helps. Kindly let us know.