How do I center an image in Bootstrap?

Question

I'm trying to horizontally center an image in the carousel of Bootstrap 4 Alpha 6.

It doesn't seem to work in any way I've tried, including using center-block.

Here's what I've tried so far: http://codepen.io/anon/pen/wJdjQg?editors=1100

Any hints?

Answer 1

center-block has been replaced by mx-auto in Bootstrap 4. mx-auto represents auto x-axis margins (margin=left: auto; margin-right: auto) so it can be used to center display:block or display:flex elements.

<div class="carousel-item active">
          <img class="img-fluid mx-auto" src="https://unsplash.it/200/200" alt="First slide">
</div>

More on Centering in Bootstrap 4

Answer 2

Found a solution:

.carousel-item img {
    margin: 0 auto;
}