Vue star score, star height displayed as 0

from the display of the browser, there is a change in the position of the five stars, but the height is 0.

here is my code:

          <div class="star-wrapper">
            <star :size="48" :score="seller.score"></star>
          </div>

<template>
  <div class="star" :class="starType">
    <span v-for="(itemClass,index) in itemClasses" v-bind:key="index" :class="itemClass" class="star-item" ></span>
  </div>
</template>

<script type="text/ecmascript-6">
  const LENGTH = 5;
  const CLS_ON = "on";
  const CLS_HALF = "half";
  const CLS_OFF = "off";
  export default {
    props: {
      size: {
        type: Number
      },
      score: {
        type: Number
      }
    },
    computed: {
      starType () {
        return "star-" + this.size;
      },
      itemClasses () {
        let result = [];
        let score = Math.floor(this.score * 2) / 2;
        let hasDecimal = score % 1 !== 0;
        let integer = Math.floor(score);
        for (let i = 0; i < integer; iPP) {
          result.push(CLS_ON);
        }
        if (hasDecimal) {
          result.push(CLS_HALF);
        }
        while (result.length < LENGTH) {
          result.push(CLS_OFF);
        }
        return result;
      }
    }
  };
</script>

<style lang="stylus" rel="stylesheet/stylus">
  @import "../../common/stylus/mixin";
  .star
    font-size:0
    .star-item
      dispaly: inline-block
      background-repeat: no-repeat
    &.star-48
      .star-item
        width: 20px
        height: 20px
        margin-right: 22px
        background-size: 20px 20px
        &: last-child
          margin-right: 0
        & .on
          bg-image("star48_on")
        & .half
          bg-image("star48_half")
        & .off
          bg-image("star48_off")
    &.star-36
      .star-item
        width: 15px
        height: 15px
        margin-right: 6px
        background-size: 15px 15px
        &:last-child
          margin-right: 0
        &.on
          bg-image("star36_on")
        &.half
          bg-image("star36_half")
        &.off
          bg-image("star36_off")
    &.star-24
      .star-item
        width: 10px
        height: 10px
        margin-right: 3px
        background-size: 10px 10px
        &:last-child
          margin-right: 0
        &.on
          bg-image("star24_on")
        &.half
          bg-image("star24_half")
        &.off
          bg-image("star24_off")
</style>

changing the height does not work. What is the cause of this and how to solve it?
Thank you!