Mastering Bootstrap 4 - Second Edition

Container

The container class renders the contents of the page to a fixed width. This width is typically based upon the width of the viewport, leveraging CSS media queries to determine which width is most suitable. These media queries are expressions that resolve to a boolean (true or false) value. By using these queries, one can apply different style rules—known as media rules—based on different viewport properties. In the case of the grid system, Bootstrap uses these media queries and the viewport's width to determine the fixed width to apply to a container's content. In order to achieve this adjustment of width, the media rules triggered by the media queries work in conjunction with breakpoints. Breakpoints in relation to web development ...