* Add chrome.css and general.css to override default css file. This is
necessary to fix links without underline (hyperlinks relying only on
color).
* Fix pop-out button without id and wrong ARIA-ROLE
* Speaker's notes now at correct heading sequence (H3)
Initially, I also formatted the templates in `theme/`, but this triggers
https://github.com/prettier/prettier/issues/11834. So I exclude them for
now.
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Co-authored-by: Ming-Ying Chung <mych@chromium.org>
