Responsive Images
<img src="..." class="img-fluid" alt="Responsive image">Image thumbnails
<img src="..." alt="..." class="img-thumbnail">Aligning images
<img src="..." class="rounded float-left" alt="...">
<img src="..." class="rounded float-right" alt="..."><img src="..." class="rounded mx-auto d-block" alt="..."><div class="text-center">
<img src="..." class="rounded" alt="...">
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