самый простой способ инвертировать CSS в темный режим

// easist way to make dark color but its not complete perfect but mostly 
// works 

html.dark-mode {
    filter: invert(100%);
}
// if you want make sure primary color should not change
html.dark-mode{
filter: invert(100%) hue-rotate(180deg);
}

html.dark-mode img {
    filter: invert(100%);
}
code fighter