Ability to support 'dark mode' styling

Current web accessibility guidelines suggest that Web Designers should offer a 'dark mode' for visitors that may prefer it, or need it. Some websites now show a 'toggle' that allows the visitor to switch between 'light' and 'dark' modes, while others will automatically switch the colours of the site depending on the user's browser/system display preferences. 

It would be amazing if WebWave enabled us to build sites where we could specify an alternative 'dark mode' style for elements - and perhaps also a preference to 'auto-select mode based on visitor preference', as well as an automatic 'dark mode toggle' button that we could place somewhere on the interface...