微信小程序实现蒙版弹窗效果

<view class="modaldlg" wx:if="{{showmodal}}">
 <view class='close_mask' bindtap="close_mask">x</view>
 <input class='recharge_amount' type='text' placeholder='充值金额' maxlength="8" value='{{recharge_amount}}'></input>
 <button class='save_money' type='submit'>立即充值</button>
</view>
 <button class='recharge' bindtap="submit">充值</button>
<view class="mask" catchtouchmove="preventtouchmove" wx:if="{{showmodal}}"></view>

// 点击充值弹窗
 submit: function () {
 this.setdata({
 showmodal: true
 })
 },
 preventtouchmove: function () {
 
 },
 
 
 close_mask: function () {
 this.setdata({
 showmodal: false
 })
 },

/* 点击充值弹窗 */
 
.mask {
 width: 100%;
 height: 100%;
 position: fixed;
 top: 0;
 left: 0;
 background: #000;
 z-index: 9000;
 opacity: 0.7;
}
 
.modaldlg {
 width: 580rpx;
 height: 450rpx;
 position: fixed;
 top: 50%;
 left: 0;
 z-index: 9999;
 margin: -370rpx 85rpx;
 background-color: #fff;
 border-radius: 36rpx;
 display: flex;
 flex-direction: column;
 align-items: center;
}
 
.recharge_amount {
 color: #aaa;
 width: 450rpx;
 height: 80rpx;
 background: #f1f1f1;
 text-align: center;
 border-radius: 12rpx;
 margin-top: 56rpx;
 text-indent: 0;
}
 
.save_money {
 color: #fff;
 width: 270rpx;
 height: 80rpx;
 line-height: 80rpx;
 background: #d95155;
 text-align: center;
 border-radius: 12rpx;
 margin-top: 80rpx;
 font-size: 28rpx;
 text-indent: 0em;
}
 
.close_mask {
 color: #000;
 position: relative;
 left: 40%;
 /* top: -82%; */
 font-size: 32rpx;
}
 
/*弹窗结束 */