W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
  <title>Light Switch</title>
  <style>
    #app {
      border: dashed black 1px;
      display: inline-block;
      padding-bottom: 10px;
    }

#app > button {
      display: block;
      margin: auto;
    }

#lightDiv {
      position: relative;
      width: 150px;
      height: 150px;
    }

#lightDiv > img {
      position: relative;
      width: 100%;
      height: 100%;
    }

#lightDiv > div {
      position: absolute;
      top: 10%;
      left: 10%;
      width: 80%;
      height: 80%;
      border-radius: 50%;
      background-color: yellow;
    }
  </style>
</head>
<body>

<h1>Example: v-on Shorthand '@'</h1>
<p>With the v-on shorthand we can write '@:click' instead of 'v-on:click'.</p>
<div id="app">
  <div id="lightDiv">
    <div v-show="lightOn"></div>
    <img src="img_lightBulb.svg">
  </div>
  <button @:click=" lightOn =! lightOn ">Switch light</button>
</div>

</body>
</html>