[eschwartz]

Sigil will create these classes with one of its options for moving style definitions outside of the text itself.

EDIT: http://web.sigil.googlecode.com/git/...faq_formatting

What does sgc-1 mean in my document?

sgc indicates a Sigil class that is used to set the formatting style for certain parts of your text. sgc classes are automatically created for certain span tags and "style=" attributes if you have HTML Tidy turned on (Edit→Clean Source).

regex

Find:

[a-zA-Z.]+ \{font-(style|weight): (italic|bold)}

Replace:

.\2 {font-\1: \2}