图片背景自适应

        .item {

            // 内容背景图片样式
            .contentBg {
                width: 100%;
                height: 100%;
                background-position: center center;
                background-size: contain;
                background-repeat: no-repeat;
                background-image: url(7.png);
            }

            .contentBg:hover {
                transform: translateZ(0) scale(1.05);
            }
        }