- I didn't need to install sass, just compiling sakai worked for me.
- I didn't use "-P compile-skin"
- after you compile, check if this folder exists: /reference/library/src/webapp/skin/morpheus-default and if the change you made shows up in any of the resulting .css files (usually tool.css)
- check the tomcat folder's /webapps/library/skin/morpheus-default/ .css files for the changes you made
- depending what what you are editing in _default.css (especially colors), you may need to include !default
- I had trouble using _customization.css. some options like the main logo or fonts worked, but changing colors for the background did not. So, I'm only using _default.css for my changes.