Rename nav.php to side-panel.php to host both navigation and table of contents
views. The panel uses data-view attributes to switch between nav and toc content.
Footer buttons updated to target the unified panel. TOC button now visible on desktop.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Rename all src/*.css to src/_*.scss partials and convert style.css
to style.scss with SASS imports.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
