I can't reproduce the problem but I run into another error: When adding
<style>.slider-callout{display:none;}</style>

the part
{display:none;}

gets removed and all that is left is
<style type="text/css">.slider-callout</style>

<style>.slider-callout{display:none;}</style>

in a question or group is not a valid HTML.
<style> tags are only allowed in the HEAD of a HTML document and even then it is bad style ;)