Consolidate all pages under a single page layout

This will help with a homogeneous look and feel as well as implements the performance and accessibility decisions made.

The issue does not identify page files, a shared layout entry point, tests, or the specific performance and accessibility decisions. Start by locating the page templates and any existing layout structure, then review how each page is rendered. Done means all pages use one layout and the stated look-and-feel, performance, and accessibility goals are implemented.

Written by the indexing model from the issue text.