CSS - 偽元素 - ::after 屬性

CSS 中的::after偽元素用於使用content屬性在選定元素之後新增內容。它允許您插入文字、影像或裝飾性元素，而無需修改 HTML 結構。預設情況下，它是內聯的。

語法

selector::after {
   /* ... */
}

不建議使用::after偽元素新增內容，因為它可能無法被螢幕閱讀器訪問。

CSS ::after 示例

這是一個簡單的::after偽元素用法示例

<html>
<head>
<style>
   p {
      color: royalblue;
      font-size: 1.5em;
      border: 2px solid black;
      text-transform: lowercase;
   }
   p::after {
      content: url(images/logo.png) ;
      position: relative;
   }
</style>
</head>
<body>
   <div>
      <p>With pseudo-element ::after</p>
   </div>
</body>
</html>

這是另一個示例，演示了::after偽元素與其他元素一起使用的情況

<html>
<head>
<style>
   body {
      width: 100%;
      height: 100vh;
      display: grid;
   }
   .glow {
      padding: 10px;
      width: 250px;
      height: 50px;
      color: #fff;
      background: #111;
      cursor: pointer;
      position: relative;
      z-index: 0;
      border-radius: 20px;
   }
   .glow::before {
      content: '';
      background: linear-gradient(60deg, #ff0000, #ff7300, #fffb00, #48ff00, #00ffd5, #002bff, #7a00ff, #ff00c8, #ff0000);
      position: absolute;
      top: -4px;
      left:-4px;
      background-size: 400%;
      z-index: -1;
      filter: blur(15px);
      width: calc(100% + 6px);
      height: calc(100% + 6px);
      animation: glowing 20s linear infinite;
      opacity: 0;
      transition: opacity .3s ease-in-out;
      border-radius: 10px;
   }
   .glow:active {
      color: rgb(246, 235, 235)
   }
   .glow:active::after {
      background: transparent;
   }
   .glow:hover::before {
      opacity: 1;
   }
   .glow::after {
      z-index: -1;
      content: '';
      position: absolute;
      width: 100%;
      height: 100%;
      background: #111;
      left: 0;
      top: 0;
      border-radius: 20px;
      background: linear-gradient(60deg, #293deb, #d019b4, #e6ac0c, #d95909, #d2ef13, #0ce45f, #a872e1, #e70db8, #2f09c8);
   }
   @keyframes glowing {
      0% { background-position: 0 0; }
      50% { background-position: 400% 0; }
      100% { background-position: 0 0; }
   }
</style>
</head>
<body>
   <button class="glow" type="button">HOVER OVER & CLICK!</button>
</body>
</html>

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