我需要底部的按钮能覆盖map组件，用的cover-view,但是cover-view不支持背景渐变色的样式，比如底部的在线预约在真机上不显示，另外，我设置的

border-radius:40rpx 0 0 40rpx;在真机上的显示的四个角全部圆角了

<cover-view class='bot'>

    <cover-view class='bot-con'>

      <cover-view class="sc {{sc == 1?'cur':''}}"   bindtap='collect'>

        <cover-image class='d-sc' src="../../images/{{sc == 1?'mysc':'shoucang'}}.png"></cover-image>

        <cover-view class='collect'>收藏</cover-view>

      </cover-view>

      <cover-view class="btns {{detail.status==1?'disable':''}}">

        <cover-view class="{{detail.status==1?'dis':'none'}}"></cover-view>

        <cover-view class='tel-order' data-tel="{{detail.guanjia.mobile}}" bindtap='call'>电话预约</cover-view>

        <cover-view class='nav online-order' bindtap='lineCollect' >在线预约</cover-view>

      </cover-view>

    </cover-view>

  </cover-view>

.online-order{-webkit-border-radius:0 40rpx 40rpx 0;-moz-border-radius:0 40rpx 40rpx 0;border-radius:0 40rpx 40rpx 0;height:80rpx;line-height:80rpx;color:#fff;-webkit-background-image:-webkit-gradient(linear,0% 0%,100% 0%,from(#ffca4d),to(#fd9840));-moz-background-image:-webkit-gradient(linear,0% 0%,100% 0%,from(#ffca4d),to(#fd9840));-o-background-image:-webkit-gradient(linear,0% 0%,100% 0%,from(#ffca4d),to(#fd9840));background-image:-webkit-gradient(linear,0% 0%,100% 0%,from(#ffca4d),to(#fd9840));}

你好，请具体描述问题出现的流程，并提供能复现问题的简单代码片段（https://developers.weixin.qq.com/miniprogram/dev/devtools/minicode.html）。