Twitter Bootstrap is a CSS framework for creating mobile-first, responsive websites. The collection of CSS classes leverage media queries under the hood to show, hide, resize, and reposition the elements in your page for mobile, tablet, and desktop users, allowing you to focus more on the content of your site and less on position and layout. Bootstrap won’t solve all your layout concerns, but you can easily drop into regular CSS to round out your site. This code-focused demo will walk us through many common Bootstrap tools and techniques, frequently resizing the browser to simulate mobile users’ experience with our content. Level up your CSS abilities with Bootstrap.