Why do some answers lose formatting when toggling between Design and Source mode?
Answers / HTML Editor
We use Tidy as our XHTML normalizer in the Answer Editor. According to our Development team, when an agent switches modes from Source -> Design -> Source, Tidy strips <style> HTML element from HTML body and attempts to move to <header> section; however, header is not a part of Answer content. This is by design, i.e., Tidy always remove everything outside the body tag.
Essentially, as <head> content elements such as <link> are intended to be inserted into the <head> section of the answer page, and the answer content is intended to be <body> content only.
To resolve this behavior, one option might be to insert the stylesheet link on your answers view page in Customer Portal. This is how stylesheets are intended to be used in the Oracle RightNow solution, and will apply it to all of your answers by default.
For additional information regarding the Tidy XHTML normalizer, please see Answer ID 2673: Modifications to the HTML source of documents.