In this Responsive Web Design Certification, I would learn the languages developers use to build webpages: HTML (Hypertext Markup Language) for content and CSS (Cascading Style Sheets) for design. First, I would build a cat photo app to learn the basics of HTML and CSS. Later, I would learn modern techniques like CSS variables by building a penguin and best practices for accessibility by building a web form. Finally, I would learn to make web pages that respond to different screen sizes by building a Twitter card with Flexbox and a complex blog layout with CSS Grid.