I went with "manually" using the same breakpoints in Bootstrap 4 as media queries...
/* Equal-height card images, cf. https://stackoverflow.com/a/47698201/1375163*/
.card-img-top {
/*height: 11vw;*/
object-fit: cover;
}
/* Small devices (landscape phones, 576px and up) */
@media (min-width: 576px) {
.card-img-top {
height: 19vw;
}
}
/* Medium devices (tablets, 768px and up) */
@media (min-width: 768px) {
.card-img-top {
height: 16vw;
}
}
/* Large devices (desktops, 992px and up) */
@media (min-width: 992px) {
.card-img-top {
height: 11vw;
}
}
/* Extra large devices (large desktops, 1200px and up) */
@media (min-width: 992px) {
.card-img-top {
height: 11vw;
}
}
It works, though I wish there were more native responsiveness of this sort.
Partial suggestion from @sepuckett86 and I.