I need a clean, responsive banner added to my existing web application that points users to our mobile app. The banner must sit at the very top of the page and appear only on the specific pages I’ll identify once we start (not site-wide). All I’m after is a lightweight, well-styled component—HTML, CSS, and a touch of JavaScript if needed—that blends with the current layout and routes users directly to the App Store and Google Play links I’ll provide. Please keep load times and mobile friendliness in mind, and deliver code that I can drop straight into my project without refactoring other assets.