<div id="app">
  <img v-bind:src="'https://via.placeholder.com/' + size" >
</div>

html, body {
  display: grid;
  justify-content: center;
  align-content: center;
  height: 100%;
  
  font-family: sans-serif;
  font-size: 1rem;
}

const app = Vue.createApp({
  data: function () {
    return {
      size: 150
    }
  }
})

const vm = app.mount('#app')