.sobre {
    background: linear-gradient(rgba(0, 0, 0, 0.2), rgba(0, 0, 0, 0.5)), url("../img/bg-sobre.jpg") left center;
    background-size: cover;
    background-position: 0 -50px;
    background-attachment: fixed;
}

.carousel-inner {
    height: 0;
    padding-bottom: 25%; /* this sets carousel aspect ratio (4:1 here) */
}
  
.carousel-item {
    position: absolute !important; /* Bootstrap is insistent */
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
}
  
.carousel-item img {
    height: 100%; /* Bootstrap handles width already */
    object-fit: cover; /* cover or 'contain' if you want stretch instead of crop */
}

.drk:after {
    content: "";
    display: block;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    background: black;
    opacity: 0.6;
    z-index: 1;
}
  
.carousel-caption {
    z-index: 2;
}