To reproduce:
-dnd button
-paste following lines into Style text area:
    .root { abc: #f00 }
    .button { -fx-background-color: abc }
-it's expected that there will be an assertion about invalid input or result inside "Inline styles" of Analyzer. But neither first nor second is true.

p.s. example of input is taken from http://docs.oracle.com/javafx/2/api/javafx/scene/doc-files/cssref.html#typecolor