I'm writing an online textbook (link) that's organized into many sections and subsections, and I've currently got it in a basic Wordpress template with an accordion menu on the left side:
This works, but it doesn't leave enough width for the content (especially some of the tables), and I want to move it up to a horizontal position at the top of the page. What's the best layout for this? What are some examples of sites with a similar amount/structure of content that do navigation well? Everything I can find seems oriented towards very different types of content.
EDIT: Thanks for the responses so far. I'm persuaded that a horizontal menu on top is a bad idea. I think I'll try to shorten the menu items in the left column and get a few more pixels of width that way, and maybe reformat some of the tables too. If that still doesn't work, I'll think about 100% width and/or making the menu retractable, as suggested.
To elaborate a little, i see three main use cases:
(1) a user who starts on the front page and wants to browse around.
(2) a user who googles a specific subtopic and lands right on that page, and may or may not browse other pages from there. (this is most of current traffic, but the site's not really done yet.)
(3) a user who starts on the front page and wants to go through all the content in order, probably in multiple visits and/or by printing it out.
User (3) obviously needs the table of contents least, and user (1) needs it most. I don't see a practical way to discriminate among them, though -- except by steering user 3 to a PDF or some other format...?