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.
Image thumbnails
In addition to our
border-radius utilities, you
can use .img-thumbnail to give an image a rounded 1px border appearance.
Aligning images
Align images with the
helper float classes
or
text alignment
classes. block-level images can be centered using the .mx-auto margin
utility class.
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>