I need some help from the HTML/Website oracle.

I'm generating html files from a C# app - they're basically log files
for our application, so while they're html they won't actually be on the
web.

What I want to do is be able to "hide" text in certain cases, so that
clicking on a link above it will toggle hiding/showing it.  I know this
was mentioned here a quite a while ago, but I can't find it on google.  
I have seen a couple of methods for doing this, but they all seem very
complex and browser-specific.  I need it to be able to work in Firefox
and IE, and since I have to physically type all the necessary code into
my c# app so that it can print it out to the html files when they're
generated, I'd prefer it if it could be fairly compact as well.

Any ideas?