public/index.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>cdg.sh</title>
  <link rel="stylesheet" href="styles.css">
</head>
<body>
  <header>
    <img class="logo" src="https://i.imgur.com/qXe7lWg.png">
  </header>
  <main id="app">
    <form class="form" v-if="formVisible" @submit.prevent="createUrl()">
      <div v-if="error" class="error">
        {{error}}
      </div>
      <input class="input" type="text" v-model="url" name="url" id="url" placeholder="enter a url">
      <input class="input" type="text" v-model="slug" name="slug" id="slug" placeholder="enter a slug">
      <button type="submit" class="create">create</button>
    </form>
    <div v-if="created">
      <p class="created">Your short url is: <a :href="created">{{created}}</a></p>
    </div>
  </main>
  <script src="https://unpkg.com/vue@2.6.11/dist/vue.js"></script>
  <script src="app.js"></script>
</body>
</html>