HTML5 themes/templates charcoal_grey, indigo not available

Report · Jul 12, 2023

I wanted to use the theme charcoal_grey for a HTML5 help output.

In Publish Settings, I clicked on Responsive HTML5, then under Manage Layout I clicked on "New" and choose Charcoal_Grey. I left all settings as they were to get a test output file first.
But instead, it showed me a cryptic message in the log, that screen layouts are not in the settings file.
("In dieser Ausgabe verwendete Bildschirmlayouts sind nicht in der Einstellungsdatei enthalten.")

After a while I tried to check the Charcoal_Grey files in the installation directory, but there are none.

Why are those files not there? How can I use the Charcoal_Grey theme??