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

## v5.2.0

### New `_maps.scss`

Bootstrap v5.2.0 introduced a new Sass file, `_maps.scss`, that pulled out several Sass maps from `_variables.scss` to fix an issue where updates to an original map were not applied to secondary maps that extend them. For example, updates to `$theme-colors` were not being applied to other theme maps that relied on `$theme-colors`, breaking key customization workflows. In short, Sass has a limitation where once a default variable or map has been _used_, it cannot be updated.

This is why variable customizations in Bootstrap have to come after `@import "functions"`, but before `@import "variables"` and the rest of our import stack. The same applies to Sass maps—you must override the defaults before the defaults get used. The following maps have been moved to the new `_maps.scss`:

- `$theme-colors-rgb`
- `$utilities-colors`
- `$utilities-text`
- `$utilities-text-colors`
- `$utilities-bg`
- `$utilities-bg-colors`
- `$negative-spacers`
- `$gutters`

Your custom Bootstrap CSS builds should now look something like this with a separate maps import.

```diff
  // Functions come first
  @import "functions";

  // Optional variable overrides here
+ $custom-color: #df711b;
+ $custom-theme-colors: (
+   "custom": $custom-color
+ );

  // Variables come next
  @import "variables";

+ // Optional Sass map overrides here
+ $theme-colors: map-merge($theme-colors, $custom-theme-colors);
+
+ // Followed by our default maps
+ @import "maps";
+
  // Rest of our imports
  @import "mixins";
  @import "utilities";
  @import "root";
  @import "reboot";
  // etc
```

### Key changes

- **Introduced new `$enable-container-classes` option.** Now when opting into the experimental CSS Grid layout, `.container-*` classes will still be compiled, unless this option is set to `false`.
- **Thicker table dividers are now opt-in.** We've removed the thicker and more difficult to override border between table groups and moved it to an optional class you can apply, `.table-group-divider`. [See the table docs for an example.]({{< docsref "/content/tables#table-group-dividers" >}})

## Dependencies

- Dropped jQuery.
- Upgraded from Popper v1.x to Popper v2.x.
- Replaced Libsass with Dart Sass as our Sass compiler given Libsass was deprecated.
- Migrated from Jekyll to Hugo for building our documentation

## Browser support

- Dropped Internet Explorer 10 and 11
- Dropped Microsoft Edge < 16 (Legacy Edge)
- Dropped Firefox < 60
- Dropped Safari < 12
- Dropped iOS Safari < 12
- Dropped Chrome < 60

<hr class="my-5">

## Documentation changes

- Redesigned homepage, docs layout, and footer.
- Added [new Parcel guide]({{< docsref "/getting-started/parcel" >}}).
- Added [new Customize section]({{< docsref "/customize/overview" >}}), replacing [v4's Theming page](https://getbootstrap.com/docs/4.6/getting-started/theming/), with new details on Sass, global configuration options, color schemes, CSS variables, and more.
- Reorganized all form documentation into [new Forms section]({{< docsref "/forms/overview" >}}), breaking apart the content into more focused pages.
- Similarly, updated [the Layout section]({{< docsref "/layout/breakpoints" >}}), to flesh out grid content more clearly.
- Renamed "Navs" component page to "Navs & Tabs".
- Renamed "Checks" page to "Checks & radios".
- Redesigned the navbar and added a new subnav to make it easier to get around our sites and docs versions.
- Added new keyboard shortcut for the search field: <kbd>Ctrl + /</kbd>.

## Sass

- We've ditched the default Sass map merges to make 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]({{< docsref "/customize/sass#maps-and-loops" >}}).

- <span class="badge bg-danger">Breaking</span> Renamed `color-yiq()` function and related variables to `color-contrast()` as it's no longer related to YIQ color space. [See #30168.](https://github.com/twbs/bootstrap/pull/30168/)
  - `$yiq-contrasted-threshold` is renamed to `$min-contrast-ratio`.
  - `$yiq-text-dark` and `$yiq-text-light` are respectively renamed to `$color-contrast-dark` and `$color-contrast-light`.

- <span class="badge bg-danger">Breaking</span> Media query mixins parameters have changed for a more logical approach.
  - `media-breakpoint-down()` uses the breakpoint itself instead of the next breakpoint (e.g., `media-breakpoint-down(lg)` instead of `media-breakpoint-down(md)` targets viewports smaller than `lg`).
  - Similarly, the second parameter in `media-breakpoint-between()` also uses the breakpoint itself instead of the next breakpoint (e.g., `media-between(sm, lg)` instead of `media-breakpoint-between(sm, md)` targets viewports between `sm` and `lg`).

- <span class="badge bg-danger">Breaking</span> Removed print styles and `$enable-print-styles` variable. Print display classes are still around. [See #28339](https://github.com/twbs/bootstrap/pull/28339).

- <span class="badge bg-danger">Breaking</span> Dropped `color()`, `theme-color()`, and `gray()` functions in favor of variables. [See #29083](https://github.com/twbs/bootstrap/pull/29083).

- <span class="badge bg-danger">Breaking</span> Renamed `theme-color-level()` function to `color-level()` and now accepts any color you want instead of only `$theme-color` colors. [See #29083](https://github.com/twbs/bootstrap/pull/29083) **Watch out:** `color-level()` was later on dropped in `v5.0.0-alpha3`.

- <span class="badge bg-danger">Breaking</span> Renamed `$enable-prefers-reduced-motion-media-query` and `$enable-pointer-cursor-for-buttons` to `$enable-reduced-motion` and `$enable-button-pointers` for brevity.

- <span class="badge bg-danger">Breaking</span> Removed the `bg-gradient-variant()` mixin. Use the `.bg-gradient` class to add gradients to elements instead of the generated `.bg-gradient-*` classes.

- <span class="badge bg-danger">Breaking</span> **Removed previously deprecated mixins:**
  - `hover`, `hover-focus`, `plain-hover-focus`, and `hover-focus-active`
  - `float()`
  - `form-control-mixin()`
  - `nav-divider()`
  - `retina-img()`
  - `text-hide()` (also dropped the associated utility class, `.text-hide`)
  - `visibility()`
  - `form-control-focus()`

- <span class="badge bg-danger">Breaking</span> Renamed `scale-color()` function to `shift-color()` to avoid collision with Sass's own color scaling function.

- `box-shadow` mixins now allow `null` values and drop `none` from multiple arguments. [See #30394](https://github.com/twbs/bootstrap/pull/30394).

- The `border-radius()` mixin now has a default value.

## Color system

- The color system which worked with `color-level()` and `$theme-color-interval` was removed in favor of a new color system. All `lighten()` and `darken()` functions in our codebase are replaced by `tint-color()` and `shade-color()`. These functions will mix the color with either white or black instead of changing its lightness by a fixed amount. The `shift-color()` will either tint or shade a color depending on whether its weight parameter is positive or negative. [See #30622](https://github.com/twbs/bootstrap/pull/30622) for more details.

- Added new tints and shades for every color, providing nine separate colors for each base color, as new Sass variables.

- Improved color contrast. Bumped color contrast ratio from 3:1 to 4.5:1 and updated blue, green, cyan, and pink colors to ensure WCAG 2.1 AA contrast. Also changed our color contrast color from `$gray-900` to `$black`.

- To support our color system, we've added new custom `tint-color()` and `shade-color()` functions to mix our colors appropriately.

## Grid updates

- **New breakpoint!** Added new `xxl` breakpoint for `1400px` and up. No changes to all other breakpoints.

- **Improved gutters.** Gutters are now set in rems, and are narrower than v4 (`1.5rem`, or about `24px`, down from `30px`). This aligns our grid system's gutters with our spacing utilities.
  - Added new [gutter class]({{< docsref "/layout/gutters" >}}) (`.g-*`, `.gx-*`, and `.gy-*`) to control horizontal/vertical gutters, horizontal gutters, and vertical gutters.
  - <span class="badge bg-danger">Breaking</span> Renamed `.no-gutters` to `.g-0` to match new gutter utilities.

- Columns no longer have `position: relative` applied, so you may have to add `.position-relative` to some elements to restore that behavior.

- <span class="badge bg-danger">Breaking</span> Dropped several `.order-*` classes that often went unused. We now only provide `.order-1` to `.order-5` out of the box.

- <span class="badge bg-danger">Breaking</span> Dropped the `.media` component as it can be easily replicated with utilities. [See #28265](https://github.com/twbs/bootstrap/pull/28265) and the [flex utilities page for an example]({{< docsref "/utilities/flex#media-object" >}}).

- <span class="badge bg-danger">Breaking</span> `bootstrap-grid.css` now only applies `box-sizing: border-box` to the column instead of resetting the global box-sizing. This way, our grid styles can be used in more places without interference.

- `$enable-grid-classes` no longer disables the generation of container classes anymore. [See #29146.](https://github.com/twbs/bootstrap/pull/29146)

- Updated the `make-col` mixin to default to equal columns without a specified size.

## Content, Reboot, etc

- **[RFS]({{< docsref "/getting-started/rfs" >}}) is now enabled by default.** Headings using the `font-size()` mixin will automatically adjust their `font-size` to scale with the viewport. _This feature was previously opt-in with v4._

- <span class="badge bg-danger">Breaking</span> Overhauled our display typography to replace our `$display-*` variables and with a `$display-font-sizes` Sass map. Also removed the individual `$display-*-weight` variables for a single `$display-font-weight` and adjusted `font-size`s.

- Added two new `.display-*` heading sizes, `.display-5` and `.display-6`.

- **Links are underlined by default** (not just on hover), unless they're part of specific components.

- **Redesigned tables** to refresh their styles and rebuild them with CSS variables for more control over styling.

- <span class="badge bg-danger">Breaking</span> Nested tables do not inherit styles anymore.

- <span class="badge bg-danger">Breaking</span> `.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`).

- <span class="badge bg-danger">Breaking</span> The `table-row-variant()` mixin is renamed to `table-variant()` and accepts only 2 parameters: `$color` (color name) and `$value` (color code). The border color and accent colors are automatically calculated based on the table factor variables.

- Split table cell padding variables into `-y` and `-x`.

- <span class="badge bg-danger">Breaking</span> Dropped `.pre-scrollable` class. [See #29135](https://github.com/twbs/bootstrap/pull/29135)

- <span class="badge bg-danger">Breaking</span> `.text-*` utilities do not add hover and focus states to links anymore. `.link-*` helper classes can be used instead. [See #29267](https://github.com/twbs/bootstrap/pull/29267)

- <span class="badge bg-danger">Breaking</span> Dropped `.text-justify` class. [See #29793](https://github.com/twbs/bootstrap/pull/29793)

- <span class="badge bg-danger">Breaking</span> ~~`<hr>` elements now use `height` instead of `border` to better support the `size` attribute. This also enables use of padding utilities to create thicker dividers (e.g., `<hr class="py-1">`).~~

- Reset default horizontal `padding-left` on `<ul>` and `<ol>` elements from browser default `40px` to `2rem`.

- Added `$enable-smooth-scroll`, which applies `scroll-behavior: smooth` globally—except for users asking for reduced motion through `prefers-reduced-motion` media query. [See #31877](https://github.com/twbs/bootstrap/pull/31877)

## RTL

- Horizontal direction specific variables, utilities, and mixins have all been renamed to use logical properties like those found in flexbox layouts—e.g., `start` and `end` in lieu of `left` and `right`.

## Forms

- **Added new floating forms!** We've promoted the Floating labels example to fully supported form components. [See the new Floating labels page.]({{< docsref "/forms/floating-labels" >}})

- <span class="badge bg-danger">Breaking</span> **Consolidated native and custom form elements.** Checkboxes, radios, selects, and other inputs that had native and custom classes in v4 have been consolidated. Now nearly all our form elements are entirely custom, most without the need for custom HTML.
  - `.custom-control.custom-checkbox` is now `.form-check`.
  - `.custom-control.custom-custom-radio` is now `.form-check`.
  - `.custom-control.custom-switch` is now `.form-check.form-switch`.
  - `.custom-select` is now `.form-select`.
  - `.custom-file` and `.form-file` have been replaced by custom styles on top of `.form-control`.
  - `.custom-range` is now `.form-range`.
  - Dropped native `.form-control-file` and `.form-control-range`.

- <span class="badge bg-danger">Breaking</span> 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.

- The longstanding [Missing border radius on input group with validation feedback bug](https://github.com/twbs/bootstrap/issues/25110) is finally fixed by adding an additional `.has-validation` class to input groups with validation.

- <span class="badge bg-danger">Breaking</span> **Dropped form-specific layout classes for our grid system.** Use our grid and utilities instead of `.form-group`, `.form-row`, or `.form-inline`.

- <span class="badge bg-danger">Breaking</span> Form labels now require `.form-label`.

- <span class="badge bg-danger">Breaking</span> `.form-text` no longer sets `display`, allowing you to create inline or block help text as you wish just by changing the HTML element.

- Form controls no longer used fixed `height` when possible, instead deferring to `min-height` to improve customization and compatibility with other components.

- Validation icons are no longer applied to `<select>`s with `multiple`.

- Rearranged source Sass files under `scss/forms/`, including input group styles.

<hr class="my-5">

## Components

- Unified `padding` values for alerts, breadcrumbs, cards, dropdowns, list groups, modals, popovers, and tooltips to be based on our `$spacer` variable. [See #30564](https://github.com/twbs/bootstrap/pull/30564).

### Accordion

- Added [new accordion component]({{< docsref "/components/accordion" >}}).

### Alerts

- Alerts now have [examples with icons]({{< docsref "/components/alerts#icons" >}}).

- Removed custom styles for `<hr>`s in each alert since they already use `currentColor`.

### Badges

- <span class="badge bg-danger">Breaking</span> Dropped all `.badge-*` color classes for background utilities (e.g., use `.bg-primary` instead of `.badge-primary`).

- <span class="badge bg-danger">Breaking</span> Dropped `.badge-pill`—use the `.rounded-pill` utility instead.

- <span class="badge bg-danger">Breaking</span> Removed hover and focus styles for `<a>` and `<button>` elements.

- Increased default padding for badges from `.25em`/`.5em` to `.35em`/`.65em`.

### Breadcrumbs

- Simplified the default appearance of breadcrumbs by removing `padding`, `background-color`, and `border-radius`.

- Added new CSS custom property `--bs-breadcrumb-divider` for easy customization without needing to recompile CSS.

### Buttons

- <span class="badge bg-danger">Breaking</span> **[Toggle buttons]({{< docsref "/forms/checks-radios#toggle-buttons" >}}), with checkboxes or radios, no longer require JavaScript and have new markup.** We no longer require a wrapping element, add `.btn-check` to the `<input>`, and pair it with any `.btn` classes on the `<label>`. [See #30650](https://github.com/twbs/bootstrap/pull/30650). _The docs for this has moved from our Buttons page to the new Forms section._

- <span class="badge bg-danger">Breaking</span> **Dropped `.btn-block` for utilities.** Instead of using `.btn-block` on the `.btn`, wrap your buttons with `.d-grid` and a `.gap-*` utility to space them as needed. Switch to responsive classes for even more control over them. [Read the docs for some examples.]({{< docsref "/components/buttons#block-buttons" >}})

- Updated our `button-variant()` and `button-outline-variant()` mixins to support additional parameters.

- Updated buttons to ensure increased contrast on hover and active states.

- Disabled buttons now have `pointer-events: none;`.

### Card

- <span class="badge bg-danger">Breaking</span> Dropped `.card-deck` in favor of our grid. Wrap your cards in column classes and add a parent `.row-cols-*` container to recreate card decks (but with more control over responsive alignment).

- <span class="badge bg-danger">Breaking</span> Dropped `.card-columns` in favor of Masonry. [See #28922](https://github.com/twbs/bootstrap/pull/28922).

- <span class="badge bg-danger">Breaking</span> Replaced the `.card` based accordion with a [new Accordion component]({{< docsref "/components/accordion" >}}).

### Carousel

- Added new [`.carousel-dark` variant]({{< docsref "/components/carousel#dark-variant" >}}) for dark text, controls, and indicators (great for lighter backgrounds).

- Replaced chevron icons for carousel controls with new SVGs from [Bootstrap Icons]({{< param "icons" >}}).

### Close button

- <span class="badge bg-danger">Breaking</span> Renamed `.close` to `.btn-close` for a less generic name.

- Close buttons now use a `background-image` (embedded SVG) instead of a `&times;` in the HTML, allowing for easier customization without the need to touch your markup.

- Added new `.btn-close-white` variant that uses `filter: invert(1)` to enable higher contrast dismiss icons against darker backgrounds.

### Collapse

- Removed scroll anchoring for accordions.

### Dropdowns

- Added new `.dropdown-menu-dark` variant and associated variables for on-demand dark dropdowns.

- Added new variable for `$dropdown-padding-x`.

- Darkened the dropdown divider for improved contrast.

- <span class="badge bg-danger">Breaking</span> All the events for the dropdown are now triggered on the dropdown toggle button and then bubbled up to the parent element.

- Dropdown menus now have a `data-bs-popper="static"` attribute set when the positioning of the dropdown is static, or dropdown is in the navbar. This is added by our JavaScript and helps us use custom position styles without interfering with Popper's positioning.

- <span class="badge bg-danger">Breaking</span> Dropped `flip` option for dropdown plugin in favor of native Popper configuration. You can now disable the flipping behavior by passing an empty array for [`fallbackPlacements`](https://popper.js.org/docs/v2/modifiers/flip/#fallbackplacements) option in [flip](https://popper.js.org/docs/v2/modifiers/flip/) modifier.

- Dropdown menus can now be clickable with a new `autoClose` option to handle the [auto close behavior]({{< docsref "/components/dropdowns#auto-close-behavior" >}}). You can use this option to accept the click inside or outside the dropdown menu to make it interactive.

- Dropdowns now support `.dropdown-item`s wrapped in `<li>`s.

### Jumbotron

- <span class="badge bg-danger">Breaking</span> Dropped the jumbotron component as it can be replicated with utilities. [See our new Jumbotron example for a demo.]({{< docsref "/examples/jumbotron" >}})

### List group

- Added new [`.list-group-numbered` modifier]({{< docsref "/components/list-group#numbered" >}}) to list groups.

### Navs and tabs

- Added new `null` variables for `font-size`, `font-weight`, `color`, and `:hover` `color` to the `.nav-link` class.

### Navbars

- <span class="badge bg-danger">Breaking</span> Navbars now require a container within (to drastically simplify spacing requirements and CSS required).

### Offcanvas

- Added the new [offcanvas component]({{< docsref "/components/offcanvas" >}}).

### Pagination

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

- Added `transition`s to pagination links.

### Popovers

- <span class="badge bg-danger">Breaking</span> Renamed `.arrow` to `.popover-arrow` in our default popover template.

- Renamed `whiteList` option to `allowList`.

### Spinners

- Spinners now honor `prefers-reduced-motion: reduce` by slowing down animations. [See #31882](https://github.com/twbs/bootstrap/pull/31882).

- Improved spinner vertical alignment.

### Toasts

- Toasts can now be [positioned]({{< docsref "/components/toasts#placement" >}}) in a `.toast-container` with the help of [positioning utilities]({{< docsref "/utilities/position" >}}).

- Changed default toast duration to 5 seconds.

- Removed `overflow: hidden` from toasts and replaced with proper `border-radius`s with `calc()` functions.

### Tooltips

- <span class="badge bg-danger">Breaking</span> Renamed `.arrow` to `.tooltip-arrow` in our default tooltip template.

- <span class="badge bg-danger">Breaking</span> The default value for the `fallbackPlacements` is changed to `['top', 'right', 'bottom', 'left']` for better placement of popper elements.

- <span class="badge bg-danger">Breaking</span> Renamed `whiteList` option to `allowList`.

## Utilities

- <span class="badge bg-danger">Breaking</span> Renamed several utilities to use logical property names instead of directional names with the addition of RTL support:
  - Renamed `.left-*` and `.right-*` to `.start-*` and `.end-*`.
  - Renamed `.float-left` and `.float-right` to `.float-start` and `.float-end`.
  - Renamed `.border-left` and `.border-right` to `.border-start` and `.border-end`.
  - Renamed `.rounded-left` and `.rounded-right` to `.rounded-start` and `.rounded-end`.
  - Renamed `.ml-*` and `.mr-*` to `.ms-*` and `.me-*`.
  - Renamed `.pl-*` and `.pr-*` to `.ps-*` and `.pe-*`.
  - Renamed `.text-left` and `.text-right` to `.text-start` and `.text-end`.

- <span class="badge bg-danger">Breaking</span> Disabled negative margins by default.

- Added new `.bg-body` class for quickly setting the `<body>`'s background to additional elements.

- Added new [position utilities]({{< docsref "/utilities/position#arrange-elements" >}}) for `top`, `right`, `bottom`, and `left`. Values include `0`, `50%`, and `100%` for each property.

- Added new `.translate-middle-x` & `.translate-middle-y` utilities to horizontally or vertically center absolute/fixed positioned elements.

- Added new [`border-width` utilities]({{< docsref "/utilities/borders#border-width" >}}).

- <span class="badge bg-danger">Breaking</span> Renamed `.text-monospace` to `.font-monospace`.

- <span class="badge bg-danger">Breaking</span> Removed `.text-hide` as it's an antiquated method for hiding text that shouldn't be used anymore.

- Added `.fs-*` utilities for `font-size` utilities (with RFS enabled). These use the same scale as HTML's default headings (1-6, large to small), and can be modified via Sass map.

- <span class="badge bg-danger">Breaking</span> Renamed `.font-weight-*` utilities as `.fw-*` for brevity and consistency.

- <span class="badge bg-danger">Breaking</span> Renamed `.font-style-*` utilities as `.fst-*` for brevity and consistency.

- Added `.d-grid` to display utilities and new `gap` utilities (`.gap`) for CSS Grid and flexbox layouts.

- <span class="badge bg-danger">Breaking</span> Removed `.rounded-sm` and `rounded-lg`, and introduced a new scale of classes, `.rounded-0` to `.rounded-3`. [See #31687](https://github.com/twbs/bootstrap/pull/31687).

- Added new `line-height` utilities: `.lh-1`, `.lh-sm`, `.lh-base` and `.lh-lg`. See [here]({{< docsref "/utilities/text#line-height" >}}).

- Moved the `.d-none` utility in our CSS to give it more weight over other display utilities.

- Extended the `.visually-hidden-focusable` helper to also work on containers, using `:focus-within`.

## Helpers

- <span class="badge bg-danger">Breaking</span> **Responsive embed helpers have been renamed to [ratio helpers]({{< docsref "/helpers/ratio" >}})** with new class names and improved behaviors, as well as a helpful CSS variable.
  - Classes have been renamed to change `by` to `x` in the aspect ratio. For example, `.ratio-16by9` is now `.ratio-16x9`.
  - We've dropped the `.embed-responsive-item` and element group selector in favor of a simpler `.ratio > *` selector. No more class is needed, and the ratio helper now works with any HTML element.
  - The `$embed-responsive-aspect-ratios` Sass map has been renamed to `$aspect-ratios` and its values have been simplified to include the class name and the percentage as the `key: value` pair.
  - CSS variables are now generated and included for each value in the Sass map. Modify the `--bs-aspect-ratio` variable on the `.ratio` to create any [custom aspect ratio]({{< docsref "/helpers/ratio#custom-ratios" >}}).

- <span class="badge bg-danger">Breaking</span> **"Screen reader" classes are now ["visually hidden" classes]({{< docsref "/helpers/visually-hidden" >}}).**
  - Changed the Sass file from `scss/helpers/_screenreaders.scss` to `scss/helpers/_visually-hidden.scss`
  - Renamed `.sr-only` and `.sr-only-focusable` to `.visually-hidden` and `.visually-hidden-focusable`
  - Renamed `sr-only()` and `sr-only-focusable()` mixins to `visually-hidden()` and `visually-hidden-focusable()`.

- `bootstrap-utilities.css` now also includes our helpers. Helpers don't need to be imported in custom builds anymore.

## JavaScript

- **Dropped jQuery dependency** and rewrote plugins to be in regular JavaScript.

- <span class="badge bg-danger">Breaking</span> Data attributes for all JavaScript plugins are now namespaced to help distinguish Bootstrap functionality from third parties and your own code. For example, we use `data-bs-toggle` instead of `data-toggle`.

- **All plugins can now accept a CSS selector as the first argument.** You can either pass a DOM element or any valid CSS selector to create a new instance of the plugin:

  ```js
  var modal = new bootstrap.Modal('#myModal')
  var dropdown = new bootstrap.Dropdown('[data-bs-toggle="dropdown"]')
  ```

- `popperConfig` can be passed as a function that accepts the Bootstrap's default Popper config as an argument, so that you can merge this default configuration in your way. **Applies to dropdowns, popovers, and tooltips.**

- The default value for the `fallbackPlacements` is changed to `['top', 'right', 'bottom', 'left']` for better placement of Popper elements. **Applies to dropdowns, popovers, and tooltips.**

- Removed underscore from public static methods like `_getInstance()` → `getInstance()`.
