By default, images don't have any borders:
<p>
<img src="lotus.jpg" />
</p>
But if you want they can be framed (default functionality in the article editor):
<p>
<img class="fr-bordered" src="lotus.jpg" />
</p>
Or they can have shadow:
<p>
<img class="image-with-shadow" src="lotus.jpg" />
</p>
Or they can even have overlay:
<p class="image-overlay">
<img src="lotus.jpg" />
</p>
Border-radius
