Additional levels of indentation of headings in readtheorg?

[pdblood]

Thanks for providing these themes. I followed the recently merged PR #107 by @ayys that enabled an arbitrary number of headings to be exported in the readtheorg theme, but I noticed that after heading 3 that all headings are at the same indentation level, both in the table of contents and main document. How hard would it be to allow further indentation beyond the third heading? Could someone point me to what would need to be changed? I only need one more level of indentation for my use case.

[acaire]

To achieve this, I used the H: syntax mentioned in #91:

# https://orgmode.org/manual/Export-Settings.html
#+OPTIONS: H:4