nginx is well known for being a front-end load balancer. It often sits between the client accessing the web site, and the PHP back ends that process your dynamic pages. While doing this, it will also perform admirably as a static content server. Here's how to get this going.
Nagios provides a menu that can be modified to fit individual needs. In order to facilitate changes in the menu, you will need to modify the code which is in the PHP pages. This means that the menu may reflect the style and changes you want but it also means that you will need to copy any changes to prepare for updates which may revert back to the standard installation.