In Bootstrap 4, you can add mx-auto
class to your img
tag.
For instance, if your image has a width of 75%, it should look like this:
<img class="d-block w-75 mx-auto" src="image.jpg" alt="First slide">
Bootstrap will automatically translate mx-auto
to:
ml-auto, .mx-auto {
margin-left: auto !important;
}
.mr-auto, .mx-auto {
margin-right: auto !important;
}