Blog post not displaying menu

Hi

I created a site, which all works fine, except for the blog section.

As the site uses custom page templates, I used

if (is_page('page_name')
display menu

As the menu has a class which sets the current pages hyperlink a different colour, I’ve done the above several times.

The problem comes with dynamically created pages.

If I create a blog post, such as /blog/test , I lose the menu, since I have defined that page in my header.

Is there a way around this?

Thanks