Bootstrap 4 Alpha 2.0 is out and open for use by the public. Now obviously a lot of aspects of it are still going to be changed, as it's still in development. But here are some exciting changes to the framework that have happened... Less to Sass Many people will be happy to know that Boostrap 4 is moving from Less to Sass. Sass has a wider support community, and is generally agreed upon being more developer friendly. Rem & Em Pixels have been swapped for rems and ems where appropriate to make responsive typography and component sizing even easier. Dropping IE8 Support Hopefully this will not come as a huge disappointment to you. The majority of the web development world despises Internet Exploder and is not sad to see that Bootstrap is dropping support for this old IE version. For more noteworthy changes in Bootstrap 4, you can check out the article at Developer Drive. Or you can just go directly to the source at the Bootstrap Blog.
