I absolutely do not want to remove the existing feature to maintain backward compatibility and not to annoy users who have grown used to the layout proposed by default in Sigil over the years.
Rather, I am thinking of an additional template system (maybe a
mustache?) That would give free hand to those users who want to have more influence on the layout (including class naming) of the table of contents, index, and maybe other pages in the future?
I would not like to impose my opinion, IMHO just templates would allow for a more personalized look.