The document discusses responsive design for landing pages. It explains that responsive design involves creating a single page that adapts its layout based on the width of the device viewing it. This allows one page to serve users on all devices from phones to tablets to desktops. It also provides tips for designing responsively, such as starting on the smallest viewport and continuously checking other sizes, focusing on forms and navigation, and ensuring images and third-party content also adapt well. The goal is to create a satisfying experience for users on every device size.