HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <title>div#box</title>
  <style>
    body {
      margin: 16px;
      font-family: system-ui, sans-serif;
      color: #0f172a;
    }

    div#box {
      border: 2px solid #2563eb;
      padding: 0.75rem;
      border-radius: 8px;
    }
  </style>
</head>
<body>
  <div id="box">div#box matches</div>
  <p>A paragraph without that id</p>
</body>
</html>

Lines: 0 | Characters: 0

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CSS ID Selector — type#id