HTML (HyperText Markup Language) is the standard markup language used to create web pages. It provides the structure and content of websites by using a system of tags and elements that tell web browsers how to display text, images, links, and other media.
CSS (Cascading Style Sheets) is used to style and layout web pages. It allows developers to control colors, fonts, spacing, positioning, and other visual aspects of HTML elements. CSS works alongside HTML to create beautiful and responsive user interfaces.
JavaScript is a programming language that runs in web browsers and enables interactive features on websites. It allows developers to create dynamic content, handle user interactions, validate forms, and build complex web applications. JavaScript is essential for modern web development.
Expand/collapse widgets use JavaScript to toggle a class that controls the visibility of content. When you click the button, the JavaScript function adds or removes the 'open' class from the details container, which triggers CSS transitions to smoothly animate the height change. The arrow icon also rotates to provide visual feedback.