The above example creates three equal-width columns on small, medium, large, and extra large devices using our predefined grid classes. Those columns are centered in the page with the parent .container. Breaking it down, here’s how it works: Containers provide a means to center and horizontally pad your site’s contents. Use .container for a responsive pixel width or .container-fluid for width: 100% across all viewport and device sizes.Rows are wrappers for columns. Each column has horizontal padding (called a gutter) for controlling the space between them. This padding is then counteracted…