小程序插件不能调用wx.chooseMessageFile ,报错： wx.chooseMessageFile is not a function, 如果插件要使用微信上的聊天文件，这个要如何实现?

plugin.json "pages": { "movie_index": "pages/movie/cinemas", "movie_cinema": "pages/movie_sub/cinema" } //页面跳转方法 uni.navigateTo({ //以下跳转方法都不行 ，navigateTo:fail rejected due to no permission currently url: "plugin-private://appid/pages/movie_cinema", //url:"plugin-private://appid/pages/movie_sub/cinema", //url:"pages/movie_sub/cinema", //url:"plugin://appid/yz-movies/pages/movie_sub/cinema", success: (res) => { console.log() console.log('success','plugin://yz-movies/movie_order') }, fail: (err) => { console.log('fail', err) } })

如题，用了flex布局把两个元素调整成了中间位置。但是只是在最顶上的中间位置，我希望把这两个元素放到偏底部的中间位置，请问我该怎么做？在wxss中如何进行设置？还要考虑各个机型不同的适配问题。