Muhammad Muhsin details the process of implementing a dark mode feature on a Gatsby-based website using React's Context API, which is particularly beneficial for users with light sensitivity. He begins by setting up a new Gatsby project, creating a context folder with a ThemeContext.js file, and utilizing React's createContext function to manage the theme state. The ThemeProvider component is created to wrap its children with ThemeContext.Provider, allowing the dark mode state to persist through localStorage. The implementation involves modifying the Gatsby Browser file to utilize the wrapRootElement API, editing the layout.js to conditionally render based on the dark mode state, and adding a toggle switch in the header component. Styles are then applied according to the conditional className for dark mode. Interested readers can see the project in action by visiting the GitHub repository.