W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
  <title>Input for e-mail Address</title>
  <style>
    #app {
      border: dashed black 1px;
      width: 200px;
      padding: 0 10px 10px 10px;
    }
    #app > div {
      width: 200px;
      height: 50px;
      border: solid black 1px;
      background-color: lightgreen;
    }
    #app > p {
      font-size: large;
      font-weight: bold;
    }
    .valid {
      color: green;
    }
    .invalid {
      color: red;
    }
  </style>
</head>
<body>

<h1>Example: Input for e-mail Address</h1>
<p>A watcher is set up to watch the e-mail input. The user is informed if the current e-mail address input is valid or invalid (missing @).</p>
<p>The user is also informed if the input just became valid with the last input from the keyboard.</p>
<div id="app">
  <label>
    <p>Type a valid e-mail address:</p>
    <input type="email" v-model="inpAddress">
  </label>
  <p v-bind:class="myClass"><code>{{ feedbackText }}</code></p> 
</div>

</body>
</html>