انتخاب بر اساس فرزند

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>MOHAMMAD ALI MESBAH</title>
    <style>
      div > p {
        background-color: rgb(255, 0, 0);
      }
    </style>
  </head>
  <body>
    <div>
        <p>hello</p>
      </div>
      <div>
        <b>bold</b>
      </div>
      <div>
        <p>hello</p>
        <p>hello</p>
      </div>
  </body>
</html>