.navbar-toggle {
  z-index:3;
}

.navbar-default {
  background-color:#ffffff;
  background-image:none;
}

@media screen and (min-width:768px) {
  .navbar-brand-centered {
    position:absolute;
    left:50%;
    display:block;
    width:160px;
    text-align:center;
  }
    
}

.scrool{  /* classe predefinita per lo scrool */
    width: 100%;
    height: 0 auto;
    background-color: rgb(243,243,242);
    opacity: 0.92;
    position: fixed;
    top: 0;
}

@media screen and (min-width:768px) {
  .navbar > .container .navbar-brand-centered, .navbar > .container-fluid .navbar-brand-centered {
    margin-left:-80px;
  }
}

.img-thumbnail{padding:.25rem;background-color:transparent;border:none;border-radius:.25rem;max-width:100%;height:auto}

.img-thumbnail-after{padding:.25rem;background-color:rgb(243,243,242);border:1px solid #dee2e6;border-radius:.25rem;max-width:100%;height:auto}