<view class="body">
 <view class="nav bc_white">
  <view class="{{selected?'red':'default'}}" bindtap="selected">系统提醒</view>
  <view class="{{selected1?'red':'default'}}" bindtap="selected1">优惠活动</view>
 </view>
 <view class="{{selected?'show':'hidden'}}">for system</view>
 <view class="{{selected1?'show':'hidden'}}">for activity</view>
</view>

page{background-color:#edf0f3;}
.nav{width:100%;height:100rpx;display:flex;flex-direction:row;}
.default{line-height:100rpx;text-align:center;flex:1;border-right:1px solid gainsboro;color:#000;font-weight:bold;font-size:28rpx;}
.red{line-height:100rpx;text-align:center;color:#fc5558;flex:1;border-right:1px solid gainsboro;font-weight:bold;font-size:28rpx;}
.show{display:block;text-align:center;line-height:200rpx;}
.hidden{display:none;text-align:center;line-height:200px;}

Page({
  data:{
    selected:true,
    selected1:false
    },
  selected:function(e){
    this.setData({
      selected1:false,
      selected:true
    })
  },
  selected1:function(e){
    this.setData({
      selected:false,
      selected1:true
    })
  }
})