onmouseover没有反应

onmouseover没有反应，控制台没有检测到语法错误，不知道问题在哪里

img

你把页面效果截图，看看是不是你的文字被div遮住，以下运行可以

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      #thread2,
      #thread4 {
        width: 300px;
        height: 300px;
        background-color: red;
        position: absolute;
      }
    </style>
  </head>
  <body>
    <ul style="list-style-type: none">
      <ol>
        <div class="css1">
          <div class="css2"><a id="thread1" href="">新闻</a></div>
          <div class="css3"><a id="thread3" href="">娱乐</a></div>
        </div>
      </ol>
      <ol>
        <div id="thread2"></div>
        <div id="thread4"></div>
      </ol>
    </ul>
    <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
    <script>
      $(document).ready(function () {
        $("#thread1").mouseover(function () {
          $("#thread2").css("background-color", "orange").css("z-index", "999");
        });
        $("#thread1").mouseout(function () {
          $("#thread2").css("background-color", "red").css("z-index", "1");
        });
      });
    </script>
  </body>
</html>

img


没用过jquery 感觉你好像多套了一层函数