.display-none{
    display: none;
  }
  .display-none.active{
    display: block;
    animation: appear .5s ease;
  }
  @keyframes appear {
    0%{
      opacity: 0;
    }
    100%{
      opacity: 1;
    }
  }

引用 : https://gxy-life.com/2PC/PC/PC20211211.html