Students often request a night mode or dark mode.
A common approach for web applications like ours (vs. an iPhone/Android app) is to use a browser extension / add-on that provides night mode functionality for any web page.
If you find an extension that works well with zyBooks, email firstname.lastname@example.org to let us know. We might provide recommendations here in the future based on such feedback.
Here is a list of browser extensions that other students have recommended to us so far. Please note that we have not tested these extensions, nor do we maintain them.
We'll also keep the request in mind for a built-in night mode.