Edit in JSFiddle

new Vue({
  el: '#app',
  data: {
    msg: ''
  },
  methods: {
  	onblur(e) {
    	this.msg =e.target.innerText;
    }
  }
})

<div id="app">
  <div contenteditable @blur="onblur">{{msg}}</div>
</div>

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#app {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  transition: all 0.2s;
}
div[contenteditable]{
  border:solid 1px red;
}

li {
  margin: 8px 0;
}

h2 {
  font-weight: bold;
  margin-bottom: 15px;
}

del {
  color: rgba(0, 0, 0, 0.3);
}