The huge, huge advantage of using an off-the-shelf, soon-to-be-core theme is that the quality is high, like really high. 

Of course, there is always a possibility I would want to add something (and I have an idea for a little animation in the back of my mind) so I wanted to find a way to do that without making any changes to the actual theme.

When Lewis Nyman tweeted about a funky little way to add a "dark mode", I saw my opportunity...