<div id="app">
  <button @click="show = !show">Toggle</button>
  <p v-show="show">Hello</p>
</div>

html, body {
  display: grid;
  justify-items: center;
  align-items: center;
  
  height: 100%;
  width: 100%;
}

#app {
  display: grid;
  grid-template-rows: 35px 35px;
  justify-items: center;
  align-items: center;
}

const app = new Vue({
  el: '#app',
  data: {
    show: false
  }
})