HIECHAT/frontend/src/pages/Kanban/responsive.css

@media (min-width: 390px) {
  mobile {
    width: 80%;
    height: 50%;
    border-radius: 5px;
    top: 50%;
    left: 50%;
    right: auto;
    bottom: auto;
    margin-right: -50%;
    transform: translate(-50%, -50%);
  }
}