It looks like I missed talking about 1.0.7 here... I published 1.0.7 early October. This was an important change because some names in CSS are case sensitive (i.e. classes). So I could not just transform everything to lowercase. If you are using an earlier version of #csspp I suggest you upgrade to at least 1.0.7.
The newer version, 1.0.8, includes a fix to the lexer which could have a buffer overflow. Really, all my tests proved that could not happen, but having a fix for such is always a good idea. If you are using #csspp in a secure environment, you probably want to upgrade since it could be viewed as a security issue.