Bootstrap is a front-end framework that brings consistent styling to Rock. We are currently using Bootstrap version 3.4.1. Whether you're tweaking content on a page or writing a custom template, you’ll want to get familiar with the standard HTML/CSS mark-up that Bootstrap provides. Reading through their excellent documentation in its entirety is a great way to get started. TipInterested in a Template?If you're interested in creating a new Rock theme based on an existing template, make sure it uses Bootstrap 3.4. This will save you a lot of time.