I use the Firefox plugin from Chris Pederick http://www.chrispederick.com/work/web-developer to edit externally called style sheet formatting within the editor preview window. This enables changes to be made to the styles and be immediately viewed. I then save the edited style sheet to my local hard drive and upload the saved file to the editor to overwrite the earlier version. I then exit the editor and reopen it at the relevant page, with the style sheet changes applied to the page. This is great.

 

What would be even better is if that or a similar style sheet editing application were integral to the editor, which enabled the stylesheet to be edited and saved directly to the currently open editor account to overwrithe original stylesheet. This would be similar to an edited html page being saved. Exiting and reopening the editor would then refresh the called style sheet and would display the changed formatting within the editable page.