Bootstrap 3: Migration Guide

Major Changes to the Grid

Bootstrap 3 still features a 12-column grid, but many of the CSS class names have completely changed:

container and row classes are now fluid by default so more need to use -fluid for the percentage based grid. Since there is now only one percentage-based grid, you would use a wrapper to create a fixed / pixel-based width.

There is no more span*. There is now base column unit named col that is sized using col-lg-*. So instead of span2 you’d now use col col-lg-2. This also works for offsets so offset* is now col-offset-*.