I think it's quite late for this answer. Anyway hope this will help somebody in the future. I faced the problem positioning the cards in angular. There are cards displayed for array of events. If image width of the event is big for card, the image should be shown by cropping from two sides and height of 100 %. If image height is long, images' bottom part is cropped and width is 100 %. Here is my pure css solution for this:
HTML:
<span class="block clear img-card b-b b-light text-center" [ngStyle]="{'background-image' : 'url('+event.image+')'}"></span>
CSS
.img-card {
background-repeat: no-repeat;
background-size: cover;
background-position: 50% 50%;
width: 100%;
overflow: hidden;
}