Pinafore-Web-Client-Frontend/routes/_components/HiddenFromSSR.html

<div class="{{hidden ? 'hidden' : ''}}">
  <slot></slot>
</div>
<script>
  export default {
    data: () => ({
      hidden: true
    }),
    oncreate () {
      this.set({hidden: !process.browser})
    }
  }
</script>