custom reports - negative numbers in red

[Lt. Goose]

Hi all,
I've been using gnucash for some months and lately I've been trying to
create my own reports (learning a bit of scheme in the meantime). I've
managed to render a table with the data I need (some kind of cash-flow
report that reports several accounts in columns, sorted by the date where
at least one transaction took place - so that you know your total balance
change everyday any transaction happened). I've got it running now after
some investigation.

Anyhow, what I'm trying to do now is to format the output in a fancier way,
but I cannot find the way to format a html-cell with a negative number
(using the option to display negative numbers in red). For instance, I'm
writing this and I'm getting a normal cell:

     (total-value (gnc:make-html-table-cell/markup "total-number-cell" (car
value)))

I've tried other markup texts like "neg-total-number-cell" or simply "neg"
but to no avail. Does anybody know how to format this?

And it'd be fantastic to have a reference of predefined markup texts that
are configured in the style sheets.

Thanks in advance.

Gus.