pinafore/routes/_components/NavItem.html

<a class='main-nav-link {{forceCurrent || page === name ? "selected" : ""}}'
   aria-label='{{forceCurrent || page === name ? `${label} (current page)` : label}}'
   aria-current="{{forceCurrent || page === name}}"
   href='{{href}}'>
  {{#if name === 'notifications'}}
    <div class="nav-link-svg-wrapper">
      <svg>
        <use xlink:href="{{svg}}" />
      </svg>
      {{#if numberOfNotifications}}
        <span class="nav-link-notifications" aria-hidden="true">
          {{numberOfNotifications}}
        </span>
      {{/if}}
    </div>
  {{else}}
    <svg>
      <use xlink:href="{{svg}}" />
    </svg>
  {{/if}}
  <span class="nav-link-label">{{label}}</span>
</a>
<style>
  .main-nav-link {
    border-bottom: 1px solid var(--nav-a-border);
    text-decoration: none;
    padding: 25px 20px;
    display: flex;
    justify-content: center;
    align-items: center;
  }

  .nav-link-svg-wrapper {
    position: relative;
    display: inline-block;
  }

  .nav-link-notifications {
    position: absolute;
    display: flex;
    align-items: center;
    justify-content: center;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    transform: translate(10px, 7px);
    z-index: 10;
    border: 1px solid var(--nav-bg);
    background: var(--nav-svg-fill);
    color: var(--nav-bg);
    border-radius: 100%;
    font-size: 0.9em;
    margin: 3px 0;
  }

  .main-nav-link.selected {
    border-bottom: 1px solid var(--nav-a-selected-border);
    background: var(--nav-a-selected-bg);
  }

  .main-nav-link.selected:hover {
    border-bottom: 1px solid var(--nav-a-selected-border-hover);
    background: var(--nav-a-selected-bg-hover);
  }

  .main-nav-link:hover {
    background-color: var(--nav-a-bg-hover);
    border-bottom: 1px solid var(--nav-a-border-hover);
  }

  .main-nav-link:hover .nav-link-label {
    color: var(--nav-text-color-hover);
  }
  .main-nav-link:hover svg {
    fill: var(--nav-svg-fill-hover);
  }

  .main-nav-link svg {
    width: 20px;
    height: 20px;
    display: inline-block;
    fill: var(--nav-svg-fill);
  }

  .main-nav-link .nav-link-label {
    font-size: 16px;
    color: var(--nav-text-color);
    padding-left: 10px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  @media (max-width: 991px) {
    .main-nav-link .nav-link-label {
      display: none;
    }
    .main-nav-link svg {
      width: 25px;
      height: 25px;
    }
    .main-nav-link {
      padding: 20px 0;
    }
    .nav-link-notifications {
      transform: translate(15px, 7px);
      margin: 3px 1px 4px;
    }
  }
</style>
<script>
  import { store } from '../_store/store'

  export default {
    store: () => store,
    computed: {
      numberOfNotifications: ($timelines, $currentInstance, $currentTimeline) => {
        return $currentTimeline !== 'notifications' &&
          $timelines &&
          $timelines[$currentInstance] &&
          $timelines[$currentInstance].notifications &&
          $timelines[$currentInstance].notifications.itemIdsToAdd &&
          $timelines[$currentInstance].notifications.itemIdsToAdd.length
      }
    }
  }

</script>