Documentation and examples for opting images into responsive behavior (so they never become wider than their parent) and add lightweight styles to them—all via classes
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 width.
<img class="img-fluid" src="path/to/image.jpg" />
Image thumbnails
In addition to our border-radius utilities, you can use .img-thumbnail to give an image a rounded 1px border appearance.
<img class="img-thumbnail" src="path/to/image.jpg" />
Align images
Align images with the helper float classes or text alignment classes.
<img class="float-start ..." src="path/to/image.jpg" />
<img class="float-end ..." src="path/to/image.jpg" />
Block-level
The block-level images can be centered using the .mx-auto margin utility class.
<img class="d-block mx-auto ..." src="path/to/image.jpg" />
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.
<picture>
<source srcset="..." type="image/svg+xml">
<img src="..." class="img-fluid img-thumbnail" alt="...">
</picture>