This example demonstrates how to add inline CSS to the header section of a PHP page using the "addStyle" function. The CSS rule provided defines the background color and font color of the page's body element. Package Library: The OCP Util PHP library is part of the ownCloud ecosystem, which is an open-source file sharing and collaboration platform. The library provides developers with a set of utility functions and classes for common tasks when developing custom apps and extensions for ownCloud.