四十九 首页点击商品，进入商品详情头部展示 以及滑动后的渐变

page.json中配置商品详情页相关内容

 {
     "path": "pages/details/details",
     "style": {
         "navigationBarTitleText": "商品详情",
         "enablePullDownRefresh": false,
         "app-plus": {
             "scrollIndicator": "none", // 隐藏首页的滚动条
             "titleNView": {
                 "type": "transparent",
                 "buttons": [{
                                 "type": "menu"
                         },
                         {
                                 "type": "share"
                         }
                 ]
             }
         }
 }
}