Bootstrap 4 carousel not responsive images
Look at this: http://www.consultacultura.it/portale_comunale_della_cultura.asp?IDcomune=1
Carousel images are not responsive like images under of it. They have the same class img-fluid.
Answer
This is a known issue in Bootstrap 4 Alpha 6...
https://github.com/twbs/bootstrap/issues/21611
As a workaround you can use..
.carousel-item.active,
.carousel-item-next,
.carousel-item-prev {
display: block;
}