摸索出来的文字居中 定位后怎么都不居中，，

<!--pages/fenxiang/fenxiang.wxml-->

<page>

<view class='top'>

<image class='image_a' src='http://img.xiangshu.com/Day_180404/60_650941_3a185077b85c40e.jpg' mode="aspectFill"></image>

<view class='gonggao'>

<image class='image_b' src='https://ccian.com/fenxiang1.png' mode="aspectFill"></image>

<text>公告：陈一发儿刚刚领取了5元红包</text>

</view>

</view>

<view class='bottom'></view>

</page>

/* pages/fenxiang/fenxiang.wxss */

page {

margin: 0;

padding: 0;

width: 750rpx;

overflow-x: hidden;

}

page .top {

width: 750rpx;

height: 300rpx;

position: relative;

}

page .top .image_a {

width: 750rpx;

height: 300rpx;

}

page .top .gonggao {

position: absolute;

top: 250rpx;

left: 0;

width: 750rpx;

height: 50rpx;

background: rgba(255, 255, 255, 0.2);

display: flex;

flex-direction: row;

align-items: center;

}

page .top .gonggao .image_b {

width: 33rpx;

height: 32rpx;

padding-left: 40rpx;

padding-right: 20rpx;

display: block;

}

page .top .gonggao text {

line-height: 50rpx;

font-size: 24rpx;

font-family: PingFangSC-Regular;

font-weight: 400;

color: rgba(255, 255, 255, 1);

display: block;

}