Sigil plugin to delete all classes and ids from xhtml files in an epub that are not referenced in css nor in fragment identifiers.
There is a graphical interface that allows the user to choose which classes and IDs to delete, in which files to look for them and in which attributes to look for fragment identifiers (by default they are href, src and epub:textref).
The plugin's code is licensed under the GPL v3.
The clearlooks Tk theme is licensed under the Tcl/Tk licensing terms.
Thanks to ttkthemes, from which the theme comes.