bootstrap/site/content/docs/4.3/content/images.md

layout	title	description	group	toc
docs	Images	Documentation and examples for opting images into responsive behavior (so they never become larger than their parent elements) and add lightweight styles to them—all via classes.	content	true

Responsive images

Images in Bootstrap are made responsive with .img-fluid. This applies max-width: 100%; and height: auto; to the image so that it scales with the parent element.

{{< example >}} {{< placeholder width="100%" height="250" class="bd-placeholder-img-lg img-fluid" text="Responsive image" >}} {{< /example >}}

Image thumbnails

In addition to our [border-radius utilities]({{< docsref "/utilities/borders" >}}), you can use .img-thumbnail to give an image a rounded 1px border appearance.

{{< example >}} {{< placeholder width="200" height="200" class="img-thumbnail" title="A generic square placeholder image with a white border around it, making it resemble a photograph taken with an old instant camera" >}} {{< /example >}}

Aligning images

Align images with the [helper float classes]({{< docsref "/utilities/float" >}}) or [text alignment classes]({{< docsref "/utilities/text#text-alignment" >}}). block-level images can be centered using [the .mx-auto margin utility class]({{< docsref "/utilities/spacing#horizontal-centering" >}}).

{{< example >}} {{< placeholder width="200" height="200" class="rounded float-left" >}} {{< placeholder width="200" height="200" class="rounded float-right" >}} {{< /example >}}

{{< example >}} {{< placeholder width="200" height="200" class="rounded mx-auto d-block" >}} {{< /example >}}

{{< example >}}

{{< placeholder width="200" height="200" class="rounded" >}}

{{< /example >}}

Picture

If you are using the <picture> element to specify multiple <source> elements for a specific <img>, make sure to add the .img-* classes to the <img> and not to the <picture> tag.

{{< highlight html >}} ​ {{< /highlight >}}