Images in Bootstrap 3 can be made responsive-friendly via the addition of the .img-responsive class. This applies max-width: 100%; and height: auto; to the image so that it scales nicely to the parent element.
.img-responsive
max-width: 100%;
height: auto;
<img src="..." class="img-responsive" alt="...">
<img src="/portals/0/..." alt="..." class="img-rounded"> <img src="/portals/0/..." alt="..." class="img-circle"> <img src="/portals/0/..." alt="..." class="img-thumbnail">