CSS is absolutely the right tool for constructing layouts because it allows you to make your components with a class (like "commandLine") and then control exactly how that input box lays out on the screen, not only its font and color but also height, scrolling, expanding or not with the window and content, and everything else that affects the look.
Ideally, JS is only for computation, HTML only for making content containers, and all layout and appearance is in CSS.