I do a lot of reading on my laptop and tablet. The ability to change the background-color and font-color on demand keeps my eyes and/or head from aching. If you have late night readers on your sites, they might thank you for implementing something like this. It's exceptionally easy to do with Webflow. I made the CSS sun and moon for fun. In real life, I would use a much smaller toggle that follows the reader the down the page.