css展开收起动画

需要展开的div
.floatbg{
    
    
 transform: scaleY(0);
 transition: transform 0.2s;
 transform-origin: top center;
 }
 点击展开时追加acitve
 .active{
    
    
      transform: scaleY(1);
      transition: transform 0.2s;
      transform-origin: top center;
    }