We don't have a mechanism for noticing changes to stylesheets included via the external stylesheet mechanism.
If you have
<stylesheet src="foo.css" />
in main.lzx, and you hit hit http://localhost:8080/myapps/main.lzx, then edit foo.css, then hit hit http://localhost:8080/myapps/main.lzx again, the app should be recompiled. Right now it will not be recompiled.