This document discusses techniques for digital animation. It covers new elements in HTML5 like <details> and <summary> which represent disclosure widgets. It also discusses sectioning content elements like <article>, <aside>, <nav>, and <section> that are used to divide HTML documents into sections. The document explains the document outlining algorithm and shows examples of outline views of web pages. It also promotes validating HTML and CSS to check for well-formed markup and as a debugging and quality control tool.