如下，无法用justify-content: center; align-items: center;等居中，只能用text-align: center;水平居中（如图），垂直居中没有办法。

.score_box{
  display: flex;
  position: fixed;
  align-self: flex-end;
  justify-content: center;
  align-items: center;
  /* text-align: center; */
  height: 60rpx;
  width: 120rpx;
  border-radius: 20rpx;
  border: 20rpx solid rgba(214, 235, 255, 0.5);
  color: rgb(253, 210, 145);
  font-size: 40rpx;
  font-weight: 600;
}

<cover-view class="score">
  <cover-view class="text">
    你的得分
  cover-view>
  <cover-view class="score_box">
    {{score}}
  cover-view>
  cover-view>