.bandeau-trn {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background-color: #ffc107;
    text-align: center;
    padding: 4px;
    
    transform: translateY(-28px); 
    transition: transform 0.3s ease-out;
}

/* On le remet en place au survol */
.bandeau-trn:hover {
  transform: translateY(0);
}