Maybe this is not the right place to post this question, but I hope that
someone can help me.
I'd like to mark a paragraph or a theorem with a (coloured) strip on the
left: something like this:
X Theorem blah blah blah
(Similarly I can put the theorem in a box with just the left side.)
I know that the package hhparmrk (it's in the "hh" package) does somethin=
similar, but I need something different.
Maybe there is a solution using pstricks, I don't know.
Thank you in advance