小程序页面高度不够用时，且无法改变高度

使用滚动视图（scroll-view）:

WXML页面：

<scroll-view class="scroll_view_vertical" scroll-y>
    <view class="item">line1</view>
    <view class="item">line2</view>
    <view class="item">line3</view>
    <view class="item">line4</view>
    <view class="item">line5</view>
    <view class="item">line6</view>
    <view class="item">line7</view>
    <view class="item">line8</view>
    <view class="item">line9</view>
    <view class="item">line10</view>
    <view class="item">line11</view>
    <view class="item">line12</view>
</scroll-view>

WXSS页面：

.scroll_view_vertical{
    height: 100%;
    margin-bottom: 20px;
    background-color: ghostwhite;
}
.scroll_view_horizotal{
    height: 50px;
    background-color: whitesmoke;
}
.item{
    height: 50px;
}

JSON页面：

{
  "window": {
    "navigationBarTitleText": "scroll_view"
  }
}