我正在尝试创建一个导航侧边栏。会有主项目，也会有子项目。

我尝试仅在单击父项目时显示子项目，并且当我单击子项目时，我希望活动子项目具有不同的颜色。我如何实现这一目标？

这是我到目前为止所尝试过的。

<template>
  <div>
    <nav>
      <ul>
        <li v-for="(link, index) in navLinks" :key="index">
          <router-link :to="link.path" class-active="active">
            <span class="items">
              {{ link.text }}
            </span>
          </router-link>
          <div v-if="link.sublinks && link.sublinks.length > 0"> //I want it to show only when the parent item is clicked
            <li v-for="(link, index) in belowLinks" :key="index">
              <router-link :to="link.path" class-active="sub-active"> //trying to add the sub-active class but it's not working
                <span class="sub-items">
                  {{ link.text }}
                </span>
              </router-link>
            </li>
          </div>
        </li>
      </ul>
    </nav>
  </div>
</template>

<script>
export default {
  data() {
    return {
      navLinks: [
        {
          text: 'Contact',
          path: '/contact',
          sublinks: [
            {
              text: 'Email',
              path: '/email',
            },
          ],
        },
        {
          text: 'About',
          path: '/about',
        },
      ],
      belowLinks: [
        {
          text: 'Blog',
          path: '/blog',
        },
        {
          text: 'Portfolio',
          path: '/portfolio',
        },
      ],
    };
  },
};
</script>
<style scoped >
nav {
  height: 100vh;
  display: flex;
  flex-direction: column;
  background: #040521;
  justify-content: space-between;
}
ul {
  display: flex;
  align-items: center;
  margin-block-start: 0;
  margin-block-end: 0;
  padding-inline-start: 0;
  flex-direction: column;
}
a {
  text-decoration: none;
  display: flex;
  align-items: center;
  color: white;
}
a:hover {
  color: white;
}
li {
  list-style-type: none;
  padding: 10px 0px;
  width: 100%;
}
.page-link .active,
.router-link-active {
  background-color: green;
  color: white !important;
  border-color: inherit !important;
}
.sub-active {
  background-color: yellow !important;
  color: white !important;
  border-color: inherit !important;
}
.items {
  padding: 10px 20px;
}
.sub-items {
  padding: 10px 0px 10px 40px;
}
</style>