Bootstrap/site/content/docs/4.3/migration.md

layout	title	description	group	aliases	toc
docs	Migrating to v5	Track and review changes to the Bootstrap source files, documentation, and components to help you migrate from v4 to v5.	migration	/migration/	true

Browser support

See the browser and devices page for details on what is currently supported in Bootstrap 5. Since v4, here's what's changed to our browser support:

• Dropped support for Internet Explorer 10 and 11
• Dropped support for Firefox NN - MM
• Dropped support for Safari NN
• Dropped support for iOS Safari NN
• Dropped support for Chrome NN
• Dropped support for Android NN

Sass

Changes to our source Sass files and compiled CSS.

• Removed hover, hover-focus, plain-hover-focus, and hover-focus-active mixins. Use regular CSS syntax for these moving forward. See #28267.
• Remove previously deprecated mixins
  • float()
  • form-control-mixin()
  • nav-divider()
  • retina-img()
  • text-hide() (also dropped the associated utility class, .text-hide)
  • visibility()
  • form-control-focus()
• Todo: New variables?
• Todo: Rearrange forms source files (under scss/forms/)
• Todo: Rearrange grid source files (under scss/grid/)
• Removed print styles and $enable-print-styles variable. Print display classes, however, have remained intact. See #28339.
• Dropped color(), theme-color() & gray() functions in favor of variables. See #29083
• The theme-color-level() function is renamed to color-level() and now accepts any color you want instead of only $theme-color colors. See #29083
• $enable-grid-classes doesn't disable the generation of container classes anymore See #29146
• Renamed $enable-prefers-reduced-motion-media-query and $enable-pointer-cursor-for-buttons to $enable-reduced-motion and $enable-button-pointers for brevity.
• Line heights are dropped from several components to simplify our codebase. The button-size() and pagination-size() do not accept line height parameters anymore. See #29271
• The button-variant() mixin now accepts 3 optional color parameters, for each button state, to override the color provided by color-contrast(). By default, these parameters will find which color provides more contrast against the button state's background color with color-contrast().
• The button-outline-variant() mixin now accepts an additional argument, $active-color, for setting the button's active state text color. By default, this parameter will find which color provides more contrast against the button's active background color with color-contrast().
• Ditch the Sass map merges, which makes it easier to remove redundant values. Keep in mind you now have to define all values in the Sass maps like $theme-colors. Check out how to deal with Sass maps on the [theming documentation]({{< docsref "/getting-started/theming#maps-and-loops" >}}).
• color-yiq() function is renamed to color-contrast() since it's not related to YIQ colorspace anymore — See #30168 — and related variables are renamed alongside:
  • $yiq-contrasted-threshold is renamed $min-contrast-ratio,
  • $yiq-text-dark and $yiq-text-light are respectively renamed $color-contrast-dark and $color-contrast-light.

JavaScript

Changes to our source and compiled JavaScript files.

• Dropped jQuery dependency and rewrote plugins to be in regular JavaScript.
• Removed underscore from public static methods like _getInstance() → getInstance().

Grid and layout

Changes to any layout tools and our grid system.

• Dropped .media component as it can be built with utility classes. See #28265.
• Remove position: relative from grid columns.
• The horizontal padding is added to the direct children in a row instead of the columns themselves.
  • This simplifies our codebase.
  • The column classes can now be used stand alone. Whenever they are used outside a .row, horizontal padding won't be added.
• Responsive gutter classes can be used to control the gutter width in as well horizontal, vertical or both directions.
• The gutter width is now set in rem and decreased from 30px to 1.5rem (24px).
• bootstrap-grid.css now only applies box-sizing: border-box to the column instead of resetting the global box-sizing. This way the grid system can be used, even if box-sizing: border-box in not applied to each element.

Content, Reboot, etc

Changes to Reboot, typography, tables, and more.

• [RFS]({{< docsref "/getting-started/rfs" >}}) enabled for automated font size rescaling. See #29152
• Reset default horizontal padding-left on <ul> and <ol> elements from browser default 40px to 2rem.
• Simplified table styles (no more odd top border) and tightened cell padding.
• Nested tables do not inherit styles anymore.
• .thead-light and .thead-dark are dropped in favor of the .table-* variant classes which can be used for all table elements (thead, tbody, tfoot, tr, th and td).
• The table-row-variant() mixin is renamed to table-variant() and accepts only 2 parameters: $color (colon name) and $value (color code). The border color and accent colors are automatically calculated based on the table factor variables.
• Dropped .pre-scrollable class. See #29135
• .text-* utilities do not add hover and focus states to links anymore. .link-* helper classes can be used instead. See #29267
• Drop .text-justify class. See #229793

Typography

• Removed $display-* variables for a new $display-font-sizes Sass map.
• Removed individiual $display-*-weight variables for a single $display-font-weight.
• Added two new .display-* heading styles, .display-5 and .display-6.
• Resized existing display headings for a slightly more consistent set of font-sizes.

Forms

• Rearranged form documentation under its own top-level section.
  • Split out old Forms page into several subpages
  • Moved input groups docs under new Forms section
• Rearranged source Sass files under scss/forms/, including moving over input group styles.
• Combined native and custom checkboxes and radios into single .form-check class.
  • New checks support sizing via em/font-size or explicit modifier classes now.
  • New checks now appear larger by default for improved usability.
  • Dropped .custom-control and associated classes.
  • Renamed most $custom-control variables to $form-control ones.
• Combined native and custom selects into .form-select.
  • Dropped .custom-select and associated classes.
  • Renamed most $custom-select variables to $form-select ones.
• Updated file input component with same overall design, but improved HTML.
  • Refactored .form-file markup to resolve some visual bugs while allowing translation and button text changes via HTML instead of CSS.
  • Dropped native .form-control-file and .form-control-range components entirely.
  • Renamed .custom-file to .form-file (including variables).
  • Added support for :focus and :disabled styles.
• Renamed .custom-range to .form-range (including variables).
• Dropped .form-group for margin utilities (we've replaced our docs examples with .mb-3).
• Dropped .form-row for the more flexible grid gutters.
• Dropped .form-inline for the more flexible grid.
• Dropped support for .form-control-plaintext inside .input-groups.
• Dropped .input-group-append and .input-group-prepend. You can now just add buttons and .input-group-text as direct children of the input groups.
• Form labels now require the .form-label class. Sass variables are now available to style form labels to your needs. See #30476

Components

Disabled states

• Disabled states of the buttons, close button, pagination link & form range now have pointer-events: none added. This simplifies our codebase and makes it easier to override active states in CSS. #29296.

Alerts

• Todo: Remove auto-darkening of <hr> elements in .alert-* class variants. <hr>s use rgba() for their color, so these should naturally blend anyway.

Badges

Badges were overhauled to better differentiate themselves from buttons and to better utilize utility classes.

• Todo: Removed and replaced .badge modifier classes with background utility classes (e.g., use .bg-primary instead of .badge-primary)
• Todo: Removed .badge-pill for the .rounded-pill utility class
• Todo: Removed badge's hover and focus styles for a.badge and button.badge.

Cards

• Removed the card columns in favor of a Masonry grid See #28922.
• Removed card decks in favor of the grid which adds more flexibility over responsive behaviour.

Jumbotron

• The jumbotron component is removed in favor of utility classes like .bg-light for the background color and .p-* classes to control padding.

Navbars

• All navbars now require a container within. This drastically simplifies spacing requirements and removes the need for extensive CSS overrides we added for responsive containers in v4.

Pagination

• Pagination links now have customizable margin-left that are dynamically rounded on all corners when separated from one another.

Popovers

• Renamed .arrow to .popover-arrow

Tooltips

• Renamed .arrow to .tooltip-arrow

Accessibility

• .sr-only-focusable does not require .sr-only anymore. See #28720.

Utilities

• Renamed .text-monospace to .font-monospace
• Decreased the number of responsive order utilities per breakpoint. The highest order utility with a number now is .order-5 instead of .order-12. See #28874.
• New line-height utilities: .lh-1, .lh-sm, .lh-base and .lh-lg. See [here]({{< docsref "/utilities/text#line-height" >}}).
• Added .bg-body for quickly setting the <body>'s background to additional elements.
• Todo: Drop .text-hide as it's an antiquated method for hiding text that shouldn't be used anymore
• Todo: Split utilities into property-value utility classes and helpers
• Negative margin utilities are disabled by default. You can re-enable them by setting $enable-negative-margins: true, but keep in mind this can increase the file size quite a lot.

Docs

• Removed "Wall of browser bugs" page because it has become obsolete

Build tools