The Official Bootstrap Blog

Announcements, discussions, and more for Bootstrap.

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Bootstrap 3.3.0 released

Bootstrap 3.3.0 is here! This release has been all about bug fixes, accessibility improvements, and documentation updates. We’ve had over 700 commits from 28 contributors since our last release. Woohoo!

Here are some of the highlights:

  • Added a handful of new Less variables for easier customization.
  • Removed recent progress bar changes for low percentages.
  • Removed all instances of translate3d as they improved repaint performance, but also added several cross browser bugs.
  • Added transforms to improve carousel performance in modern browsers.
  • Updated Normalize.css and our H5BP print styles to their latest releases.
  • Improved accessibility for navs, panels, tooltips, buttons, and more.
  • Resolved dozens of JavaScript and documentation bugs.

For a complete breakdown, read the release changelog or the v3.3.0 milestone.

Download Bootstrap

Download the latest release—source code, compiled assets, and documentation—as a zip file directly from GitHub:

Download Bootstrap 3.3.0

Hit the project repository or Sass repository for more options. Also, remember we’re available on npm, too.

An update for the Bootstrap CDN will be available shortly.

New tools

Since our last release, we’ve open sourced two new tools:

  • Bootlint, a custom linter for all your Bootstrap projects.
  • Rorschach, a bot for checking new pull requests for common mistakes.

They join LMVTFY, our bot for quickly validating HTML in live examples. As the project, team, and community continue to grow, look for even more awesome tools to be open sourced.

Onward to Bootstrap 4

Perhaps the best part of releasing v3.3.0 today is that we can start to tell you more about Bootstrap 4! While the first alpha is a couple weeks off, here’s a quick preview of what’s to come:

  • Updated grid system with at least one additional tier for handheld devices.
  • A brand new component to replace panels, thumbnails, and wells.
  • A completely new, simpler navbar.
  • Switch all pixel values over to rems and ems for easier and better type and component sizing.
  • Dropped support for IE8.
  • Tons of form updates, including custom form controls.
  • New component animations and transitions for several components.
  • UMD support throughout our JavaScript plugins.
  • Improved JavaScript positioning for tooltips, popovers, and dropdowns.
  • Brand new documentation (written in Markdown, too!).
  • A new approach to configuring global theming options.
  • And hundreds more changes across the board.

We’d love to tell you more, but the dust still has to settle before we open our first pull request with a live alpha release. In addition to launching in v4 in the coming months, we’ll be maintaining v3 with small bugfixes for the first few months after the new version ships.


@mdo & team

Introducing Rorschach

Bootstrap receives tons of awesome pull requests every week. Many of them come from folks new to contributing to the project. As such, there are a few beginner mistakes we’ve noticed over time.

So, we made Rorschach, a bot that runs a few quick checks on every new pull request.

Rorschach automatically gives instant feedback on Bootstrap pull requests that suffer from one of several simple mistakes, thus decreasing turnaround time on fixing the pull request. The bot refers the contributor to new documentation we’ve written to explain each of the mistakes in detail, along with how to correct them, thus decreasing friction for contributors.

Previously, these mistakes were checked for manually, which meant there was often a delay before the mistake was noticed and that pull request reviewers had to manually explain the mistake to the contributor each time. With Rorschach, everyone should have a smoother experience working on Bootstrap.

Happy pull requesting!


@cvrebert and team

Introducing Bootlint

After hanging out on the Bootstrap issue tracker for a long time, you start to notice some common mistakes folks make (besides just plain invalid HTML). Many of them are covered in our documentation, but our docs can be lengthy and some of the mistakes are pretty subtle or have non-obvious causes.

Pointing out the same mistakes repeatedly again gets tiring, so once again, we decided to try automating things. The result of our efforts is Bootlint, an HTML linting tool for projects using vanilla Bootstrap. Using Bootlint (either in-browser or from the command line via Node.js), you can automatically check your Bootstrapped webpages for many common Bootstrap usage mistakes.

We encourage you to add Bootlint to your web development toolchain so that none of the common mistakes slow down your project’s development. In the future, we hope to also make a GitHub issues bot based on Bootlint to help folks out on the Bootstrap issue tracker.

For more details, installation & usage instructions, or to contribute or give feedback, check out the Bootlint project on GitHub!


@cvrebert and team

Bootstrap 3.2.0 released

Today we’re shipping Bootstrap v3.3.7, a monster of a release that’s been in the works for four months. There’s lots of new hotness, hundreds of bug fixes, plenty of documentation improvements, and some build tool improvements. All told, there have been over 1,000 commits since our last release.

Download Bootstrap

Download the latest release—source code, compiled assets, and documentation—as a zip file directly from GitHub:

Download Bootstrap 3.2.0

Hit the project repository or Sass repository for more options. Also, remember we’re available on npm, too.

Bootstrap CDN

After reviewing the changelog, update your CDN links to point to the v3.3.7 files:

<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css">
<!-- Optional theme -->
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap-theme.min.css">
<!-- Latest compiled and minified JavaScript -->
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"></script>

What’s new

Here’s a look at some of the highlights of this release.

Responsive embeds

As seen in SUIT CSS, we’ve added a few classes for creating responsive embeds. They’re great for proportionally scaling down YouTube videos and other iframe or embed elements. Head to the docs to check them out.

New responsive utility classes

We’ve had responsive utility classes—e.g., .visible-xs—for awhile now. Today, they level up a bit. We’ve added block, inline-block, and inline variations for each grid tier. For example, .visible-xs-block is now a thing.

Copy docs snippets

Our documentation snippets just got an upgrade with the help of ZeroClipboard, the open source Flash-based copy-paste button. It’ll appear in the top right of nearly every example in the docs. Just click, and paste.


We blogged about this yesterday, but we have a new bot hanging out in our issues and pull requests on GitHub. Whenever someone pastes in a live example—like those from JS Bin or jsFiddle—we now validate their HTML. If it’s invalid, we tell folks what’s wrong so they can fix it.

Browser bugs

We’ve also begun tracking unresolved browser bugs that currently impact Bootstrap’s development in some way. We call it the Wall of browser bugs. One of the coolest parts of developing Bootstrap is finding and reporting browser bugs to their developers. We’re literally helping to make the web a better place, and that’s pretty awesome in our book.

And dozens more…

With over 1,000 commits, a lot has changed, and all of it for the better. A few more notable changes include:

  • The docs have been rearranged and updated to be more specific and easier to develop.
  • The progress bar component has been improved for increased flexibility.
  • CSS repaint performance (most notably through scrolling) has been enhanced for several components.
  • Keyboard navigation (forward and backward) is now available for the carousel.
  • Modals should no longer shift left when being opened.

For a complete breakdown, read the release changelog or the v3.3.7 milestone.

What’s next

Well, we’ll probably have a patch release (v3.2.1), and then I imagine it’s onward to v4. We have a v3.3.0 milestone on GitHub, but it’s still unclear if we’ll ship that before jumping to v4. We’ve been building a list of things we’d like to see in the new version, but we don’t have anything ready for the public yet. We’ll share more details as we have them though. Until then, enjoy!


@mdo & team

Let Me Validate That For You (LMVTFY)

If you’ve been following the Bootstrap issue tracker lately, you might have noticed the launch of our new bot, @twbs-lmvtfy, on June 15th. After seeing many reports of Bootstrap bugs that ended up actually being caused by folks using invalid HTML, we decided to do what all programmers do when confronted with a repetitive task: Automate it!

To that end, we are excited to announce the availability of Let Me Validate That For You (LMVTFY), an open-source bot that uses the power of the GitHub webhooks API and the validator.nu HTML5 validator to warn about HTML validity errors in live Web examples (e.g. JS Bins) posted to GitHub issues.

The bot is generic and can be used for any GitHub project, not just Bootstrap. If you have a front-end Web project on GitHub that gets lots of issue reports, we invite you to try out LMVTFY.

For more details, setup instructions, or to give feedback, check out the LMVTFY project on GitHub.


@cvrebert and team