CSS变量的写法，定位不到元素

原来拾取CSS元素路径："\"div:nth-child(1)>div:nth-child(16)>div:nth-child(1)>div:nth-child(1)>div:nth-child(2)>span:nth-child(1)>span:nth-child(2)>input:nth-child(1)\""

修改变量元素路径：

"\"div:nth-child(1)>div:nth-child(16)>div:nth-child(1)>div:nth-child(1)>div:nth-child(2)>span:nth-child(1)>span:nth-child(2)>input:nth-child("+idx+1+")\""

测试变量：idx 有数值，但是没有定位到元素获得焦点 点击和输入