In this Responsive Web Design Certification, you'll learn the languages that developers use to build webpages: HTML (Hypertext Markup Language) for content, and CSS (Cascading Style Sheets) for design. First, you'll build a cat photo app to learn the basics of HTML and CSS. Later, you'll learn modern techniques like CSS variables by building a penguin, and best practices for accessibility by building a quiz site. Finally, you'll learn how to make webpages that respond to different screen sizes by building a photo gallery with Flexbox, and a magazine article layout with CSS Grid.