To further specify. I put extra_css = 'p { text-align: left}' into the recipe
f_securecustom.recipe
I used the command line
ebook-convert f_securecustom.recipe .mobi --test -vv --debug-pipeline debug
The job is done.
I opened: ...\debug\structure\feed_0\article_0\index.html
Now, in the code of : the file I find:
... <p align="justify">
maybe that is the reason.
But still I do not know how to proceed?