Flexbox

Another method for creating responsive, aligned content is by using a new layout method called Flexbox. Flexbox allows items in a container to be laid out efficiently, even when the size of the container and/or items is unknown (thus the prefix flex)

Flexbox has good support on modern browsers, with the exception of bugs on Internet Explorer. That said, it's safe to say that we can use Flexbox in circumstances where we either have a fallback for IE users.

There is a great guide on Flexbox on CSS Tricks