transmission/macosx/Sparkle.framework/Versions/A/Resources/ReleaseNotesColorStyle.css

@media (prefers-color-scheme: dark) {
    html {
        color: white;
        background: transparent;
    }
    :link {
        color: #419CFF;
    }
    :link:active {
        color: #FF1919;
    }
}