Would it be possible to add a setting where one can enter a URL for a custom stylesheet - and if this setting is set, it's treated as another style to switch to? (Looking at the logic of styleswitcher-1.js this doesn't seem like a major change). This would make developing alternative styles much easier.

For instance, if I were to set the setting to 'http://www.abigail.be/style/brainking.css', I could work locally to develop a different style and if done, present it to Fencer as one of the user developped styles.