Bootstrap img src
<img src="..." class="rounded mx-auto d-block" alt="...">
Kalpataru Code
<img src="..." class="rounded mx-auto d-block" alt="...">.img-fluid
.img-thumbnail<img src="..." alt="..." class="img-thumbnail"><img src="https://chart.googleapis.com/chart?cht=qr&chl=https://covid.aminhospital.net/ValidateResult/validate/32853&chs=160x160&chld=L|0" class="qr-code img-thumbnail img-responsive" width="120" height="120">