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e4069996d8
The site/about/about.css, site/community/community.css, and
site/newsletter/newsletter.css custom styles key dark-mode CSS
variables off `.quarto-dark { ... }` (and descendant chains like
`.quarto-dark .opening-lead`). That class is added by Quarto only when
the user clicks the toggle button — never on the OS-preferred dark
path. Result: a visitor whose browser is set to dark mode but who has
not toggled the site explicitly gets the dark <html data-bs-theme=dark>
background but the LIGHT mode `--ab-text: #1a1a2e` text, producing the
classic "Open by design." invisibility on /about/license.html and a
slate of low-contrast hero/body text across about/community/newsletter
pages.
Patch the central `apply()` so every theme transition — initial paint,
toggle click, OS-pref change, cross-tab storage event — also mirrors
the scheme onto `document.body.classList`. A MutationObserver covers
the FOUC window where <body> has not yet parsed at first apply().
This is intentionally a JS bridge rather than a CSS rewrite: the three
custom-CSS files have ~15 selectors keyed on `.quarto-dark` between
them, including descendant chains where a naive find/replace would
break selector grouping (`.quarto-dark .foo {...}` cannot become
`[data-bs-theme="dark"], .quarto-dark .foo {...}` — that comma turns
the first selector standalone). One JS line covers all of them and
keeps the CSS files unchanged.