//topNavigationBar公共header组件

<topNavigationBar :defaultBack="true" titleColor="#393C42" title="购买课程"/>
                //占位view
        <view :style="{'height':navigateBarHeight + 'rpx'}">占位</view>
                //内容content 
        <view class="Content" :style="{'--height':height}">
</view>

//放到 template 里的view

data() {
    return {
        navigateBarHeight:'',
        height:'',
    }
}
created(){
        //header组件返回的高度
    this.navigateBarHeight = pageContantTop()
    this.height = this.navigateBarHeight+'rpx'
},

//content 高度样式

Content{
    height:calc(100% - var(--height) );
}