hide menu when viewing a post

I do this same thing on my NucleusCMS-based weblog, and am glad to se this particular workaround. In NucleusCMS, there is a template system which can be used to create different presentation based upon location within the weblog, i.e.: reading main page or reading a single entry.
(No, I’m not suggesting WP should go the template route! It’s fine the way it is.)
BTW: Where can I find a list of the variables WordPress uses, e.g.: $single? This could come in handy to personalize the weblog. I would much rather modify the index.php file than change the core WP code.
Thanks.
<rb>

If you’re going to code the PHP, you might as well do something as follows:
if ($single==1) {
//insert menu code here
}
The CSS method is inefficient because it makes all those function calls, including all those MySQL queries, for no effective result. For a low traffic site this may not matter, but it’s a sure way to hog system resources unnecessarily.

Individual entry look/template is a popular request and I hope WP developers will address this directly or through a plugin.