css鼠标移动上去才显示滚动条

            &::-webkit-scrollbar {
                    width: 4px;
                    background-color: #efeae6;
                }
                &:hover ::-webkit-scrollbar-track-piece {
                    /*鼠标移动上去再显示滚动条*/
                     background-color: #fff;
                     /* 滚动条的背景颜色 */
                     border-radius: 6px;
                     /* 滚动条的圆角宽度 */
                }
                &:hover::-webkit-scrollbar-thumb:hover {
                    background-color: #c1c1c1;
                }
                &:hover::-webkit-scrollbar-thumb:vertical {
                    background-color: #c1c1c1;
                    border-radius: 6px;
                    outline: 2px solid #c1c1c1;
                    outline-offset: -2px;
                    border: 2px solid #c1c1c1;
                }