How to generate a lines inside of vue-accordion on each checkbox click in Vuejs?

data: function () {
    return {
      show: false,
    };
  },
  methods: {
    toggleItem: function () {
      this.show = !this.show;
    },
  },

  <div class="wrapper">
    <div class="accordion">
      <input type="checkbox" @click="toggleItem" />

      <h2 class="title">
        <slot name="title"></slot>
      </h2>
    </div>
    <div v-show="show" class="content">
      <slot name="content"></slot>
    </div>
  </div>

I want to generate a lines like below, inside of the vue-accordion. every time. When ever user click on each checkbox separately.

So to achieve like above, do i need any other plugins or with css can i achieve that.

Working code snippet:- https://codesandbox.io/s/vue-accordion-component-forked-vwpi8?file=/src/components/Accordion.vue