Olly's very simple accordion plugin

To use, make content that looks like this:

<div class="accordion [closed]">
    <h3>Section title</h3>
    <div>Section content</div>
    <h3>Section title</h3>
    <div>Section content</div>
    [etc]
</div>

Then use $("div.accordion").ohAccordion() in document.ready().

• By default, first branch is opened.
• Supports bookmarking, e.g. this.html#expander01
• A class of closed on the top div means no branches are open by default, unless specced in the URI.
• The script will automatically add id attributes to the divs if they don't already have them, e.g. #expander01/02/03/etc.
• When open, the <h3> elements gain class="open".
• The script adds appropriate aria-* roles to the relevant elements at the relevant moments.

It's best to style it so it looks good even if the nodes are open, just in case javascript is unavailable for some reason.