This is related to Bug 594.
When using Chrome, and viewing this page:
http://www.tei-c.org/release/doc/tei-p5-doc/en/html/index.html (Guidelines TOC), the dropdown menus from the items along the top bar don't drop down.
This doesn't happen in Safari. I checked to make sure it wasn't a delay, but if it is, it's quite long.