MediaWiki:Gadget-dark-mode-toggle-pagestyles.css explained

/* Fixes for empty icons in Vector 2022 and Minerva */.mw-ui-icon-vector-gadget-pt-darkmode,.mw-ui-icon-vector-gadget-pt-darkmode-sticky-header,.minerva-icon-portletlink-pt-darkmode

.minerva-icon-portletlink-pt-darkmode

.client-dark-mode .mw-ui-icon-vector-gadget-pt-darkmode,.client-dark-mode .mw-ui-icon-vector-gadget-pt-darkmode-sticky-header,.client-dark-mode .minerva-icon-portletlink-pt-darkmode

/* These same rules should also be in but with higher specificity. */.skin-vector-legacy :not(#pt-darkmode) + #pt-watchlist::before,.skin-monobook :not(#pt-darkmode) + #pt-watchlist::before

/* Avoid showing "report an issue" - can be removed in 1.43.0-wmf.13 */.skin-vector-2022 .skin-theme-exclusion-notice ~ span