In this section, we will discuss how to import CSS frameworks and utilities into our application to set up a basic, responsive layout in our Angular application using Bootstrap. Bootstrap is a very popular CSS framework developed by Twitter for responsive web design that works on a wide range of devices, from desktop computers to mobile phones. The latest version of Bootstrap 4 includes many improvements, including switching from Less to Sass for its source files, a new flex-box-based grid system, and many optimizations and performance tweaks to better support mobile devices.