cemsdb
It's defined by this rule:
@media (max-width: 480px) {
.category-module.owl-carousel .item .item-intro {
width: 100% !important;
}
.category-module.owl-carousel .item .item-image {
width: 100% !important;
}
}
You can change both to 50% but I think it will not look nice on small screen.