How to center align img wrapped in a tag?

Question

Bootstrap

bootstrap 4

<a href="img.jpg" onclick="return hs.expand(this)" ><img class="img-fluid mx-auto d-block" src="imgsmall.jpg" alt="картинко" title="картинко"  /></a>

turns out to be pressed to the left edge

<img class="img-fluid mx-auto d-block" src="imgsmall.jpg" alt="картинко" title="картинко"  />

rises in the center
How can I put the first structure in the center?

Answer 1

center tag to help
htmlbook.ru/html/center

Answer 2

Display: block
Margin: 0 auto
For img