Migrating to v4

Bootstrap 4 is a major rewrite of the entire project. The most notable changes are summarized below, followed by more specific changes to relevant components.

Stable changes

Moving from Beta 3 to our stable v4.0 release, there are no breaking changes, but there are some notable changes.

Printing

Beta 3 changes

While Beta 2 saw the bulk of our breaking changes during the beta phase, but we still have a few that needed to be addressed in the Beta 3 release. These changes apply if you’re updating to Beta 3 from Beta 2 or any older version of Bootstrap.

Miscellaneous

Forms

Input groups

Beta 2 changes

While in beta, we aim to have no breaking changes. However, things don’t always go as planned. Below are the breaking changes to bear in mind when moving from Beta 1 to Beta 2.

Breaking

Highlights

Summary

Here are the big ticket items you’ll want to be aware of when moving from v3 to v4.

Browser support

Global changes

Grid system

Components

By component

This list highlights key changes by component between v3.x.x and v4.0.0.

Reboot

New to Bootstrap 4 is the Reboot, a new stylesheet that builds on Normalize with our own somewhat opinionated reset styles. Selectors appearing in this file only use elements—there are no classes here. This isolates our reset styles from our component styles for a more modular approach. Some of the most important resets this includes are the box-sizing: border-box change, moving from em to rem units on many elements, link styles, and many form element resets.

Typography

Images

Tables

Forms

Buttons

Button group

Grid system

List groups

The navbar has been entirely rewritten in flexbox with improved support for alignment, responsiveness, and customization.

Pagination

Labels and badges

Panels, thumbnails, and wells

Dropped entirely for the new card component.

Panels

Progress

Tables

Utilities

Vendor prefix mixins

Bootstrap 3’s vendor prefix mixins, which were deprecated in v3.2.0, have been removed in Bootstrap 4. Since we use Autoprefixer, they’re no longer necessary.

Removed the following mixins: animation, animation-delay, animation-direction, animation-duration, animation-fill-mode, animation-iteration-count, animation-name, animation-timing-function, backface-visibility, box-sizing, content-columns, hyphens, opacity, perspective, perspective-origin, rotate, rotateX, rotateY, scale, scaleX, scaleY, skew, transform-origin, transition-delay, transition-duration, transition-property, transition-timing-function, transition-transform, translate, translate3d, user-select

Documentation

Our documentation received an upgrade across the board as well. Here’s the low down:

Responsive utilities

All @screen- variables have been removed in v4.0.0. Use the media-breakpoint-up(), media-breakpoint-down(), or media-breakpoint-only() Sass mixins or the $grid-breakpoints Sass map instead.

Our responsive utility classes have largely been removed in favor of explicit display utilities.

Rather than using explicit .visible-* classes, you make an element visible by simply not hiding it at that screen size. You can combine one .d-*-none class with one .d-*-block class to show an element only on a given interval of screen sizes (e.g. .d-none.d-md-block.d-xl-none shows the element only on medium and large devices).

Note that the changes to the grid breakpoints in v4 means that you’ll need to go one breakpoint larger to achieve the same results. The new responsive utility classes don’t attempt to accommodate less common cases where an element’s visibility can’t be expressed as a single contiguous range of viewport sizes; you will instead need to use custom CSS in such cases.