Goal

This fork keeps Bootstrap 5 fully compatible with modern toolchains: Dart Sass (including the upcoming @import removal), Node.js 22, ESLint 9 flat config, Vitest and Playwright. The public API stays identical to upstream Bootstrap 5.3.

Why upgrade

Upstream 5.3.x is stable, but its toolchain and Sass sources still carry deprecations that will break or warn under Dart Sass 2/3 and modern Node. The fork removes that friction while keeping the public API identical to 5.3.8.

• Dart Sass 2/3 ready — the remaining deprecations are gone: if() function syntax, color.red()/green()/blue(), mixed-decls. Only import remains (which can be silenced), and the scss/module/ tree (@use/@forward) is ready for when it disappears.
• Drop-in total — an npm alias is all it takes: byte-identical CSS verified by golden tests, vanilla JS and Popper 2 unchanged, data-* attributes and plugin APIs identical. Nothing to rewrite.
• Incremental change — the @use migration can be done file by file: scss/ and scss/module/ coexist in the same package.
• Real confidence — 822 unit tests, 18 end-to-end tests across Chromium/Firefox/WebKit covering what jsdom cannot (focus trapping, geometry, keyboard navigation), Sass True coverage, and automated CSS parity checks between both Sass trees.
• Node.js 22 toolchain — ESLint 9 flat config, Vitest, Playwright, recalibrated bundlewatch and Dependabot: a solid base to keep patching.

In short: same Bootstrap 5, but it compiles, runs and installs like a 2026 library.

Installation

npm install bootstrap-modernized

// With @import (legacy scss/ tree, import warning can be silenced)
@import "bootstrap-modernized/scss/bootstrap";

// With @use (scss/module/ tree, recommended)
@use "bootstrap-modernized/scss/module/bootstrap";

// Bundle including Popper 2
import "bootstrap-modernized/dist/js/bootstrap.bundle";

// Standalone ESM (Popper 2 as a peer dependency)
import { Modal, Dropdown } from "bootstrap-modernized";

Sass usage

The scss/module/ tree is the recommended entry point. Configuration happens through @use ... with() on the variables module:

@use "bootstrap-modernized/scss/module/variables" as vars with (
  $primary: #0d6efd,
  $body-bg: #fafafa
);
@use "bootstrap-modernized/scss/module/bootstrap";

All functions and mixins are namespaced (variables.$primary, functions.tint-color(), mixins.media-breakpoint-up(), rfs.rfs()), so the tree works without global imports.

Compatibility

| Tool | Minimum supported | | --------------- | ----------------- | | Dart Sass | 1.79+ | | Node.js (build) | 22 LTS | | @popperjs/core | 2.11+ | | Browsers | modern + ESR |

The optional jQuery compatibility bridge still activates when window.jQuery is present, but jQuery is not a dependency of Bootstrap 5.

Demo

• Live demo (v5-modern) — the dist build exercising modal, dropdown, tooltip, popover and accordion with vanilla JS
• Live demo (v4-modern) — the v4 fork running with jQuery 4 and Popper 2

Documentation

• MIGRATION.md — changes compared to Bootstrap 5.3.8
• CHANGELOG.md
• Upstream Bootstrap 5.3 docs: https://getbootstrap.com/docs/5.3/

License

The original code is MIT licensed (Copyright Twitter, Inc. and The Bootstrap Authors). This fork adds modifications copyrighted by Guillaume Ernst, also under MIT. See LICENSE.