<div class="col-sm-6">
{% markdown %}
### Source files
-Download everything: source Sass, JavaScript, and documentation files. **Requires a Sass compiler, [Autoprefixer](https://github.com/postcss/autoprefixer), and [some setup]({{ site.baseurl }}/getting-started/build-tools/#tooling-setup).**
+Download everything: source Sass, JavaScript, and documentation files. **Requires a Sass compiler, [Autoprefixer](https://github.com/postcss/autoprefixer), [postcss-flexbugs-fixes](https://github.com/luisrudge/postcss-flexbugs-fixes), and [some setup]({{ site.baseurl }}/getting-started/build-tools/#tooling-setup).**
<a href="{{ site.download.source }}" class="btn btn-bs btn-outline" onclick="ga('send', 'event', 'Getting started', 'Download', 'Download source');">Download source</a>
{% endmarkdown %}
## Package managers
-Pull in Bootstrap's **source files** into nearly any project with some of the most popular package managers. No matter the package manager, Bootstrap will **require a Sass compiler and [Autoprefixer](https://github.com/postcss/autoprefixer)** for a setup that matches our official compiled versions.
+Pull in Bootstrap's **source files** into nearly any project with some of the most popular package managers. No matter the package manager, Bootstrap will **require a Sass compiler, [Autoprefixer](https://github.com/postcss/autoprefixer), and [postcss-flexbugs-fixes](https://github.com/luisrudge/postcss-flexbugs-fixes)** for a setup that matches our official compiled versions.
{% callout warning %}
**Heads up!** Not all package managers have the v4 alpha published yet, but we should have them up shortly!
- Input groups, which move from `display: table;` to `display: flex;`.
- The media component moves from `display: table;` and a number of hacky styles to a simple `display: flex;`.
-Vendor prefixes are provided in our compiled CSS with Autoprefixer via Grunt.
+Vendor prefixes are provided in our compiled CSS with [Autoprefixer](https://github.com/postcss/autoprefixer) via Grunt. Some bugs in IE10-11's Flexbox implementation are worked around via [postcss-flexbugs-fixes](https://github.com/luisrudge/postcss-flexbugs-fixes).
## Why flexbox?