css3 弹出层居中（防止穿透滚动）

<view class="mask" v-if="lookUpTips" @touchmove.stop.prevent="catchtouchmove"></view>
<view class="popup-draw-active" v-if="lookUpTips"  @touchmove.stop.prevent="catchtouchmove">
    lst
</view>
.mask{
        position: fixed;
        top: 0;
        left: 0;
        z-index: 10;
        background-color:rgba(0,0,0,0.9);
    }
.popup-draw-active{
        position: fixed;
        top: 50%;
        left: 50%;
        z-index: 11;
         640rpx;
        height: 600rpx;
        padding: 30rpx;
        border-radius: 24rpx;
        background-color: #ffb4c7;
        transform: translate(-50%, -50%) scale(1);
        opacity: 1;
        transition: .3s;
        line-height: 1;
        text-align: center;
        color: #282828;
        background-repeat: round;
        background-size: 100%;
}

methods: {
            catchtouchmove() {
                return;
            },
}