Sku商品购买组件，基础用法例子里，（安卓手机微信浏览器）输入input在上半屏幕里，会出现看不到输入框的位置。。。

[wwb568109135]

请认真写 PR 的标题，会用于生成 change log。

Do you want to request a feature or report a bug?
bug
What is the current behavior?
你们的在线demo例子，Sku商品购买组件，基础用法例子里，（安卓手机微信浏览器）输入input在上半屏幕里，会出现看不到输入框的位置。。。

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://jsfiddle.net or similar (template: https://jsfiddle.net/n879nke7/).

What is the expected behavior?
可以看到输入框的位置
Which versions of Vant and Vue, and which browser / OS are affected by this issue? Did this work in previous versions of Vant?

[w91]

@wwb568109135 你好，能提供下你的安卓手机系统版本和手机型号吗，我这边找了几个没试出来