HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>id scope demo</title>
  <style>
    body { font-family: sans-serif; padding: 16px; max-width: 32rem; }
    #sidebar, #main { padding: 12px; margin: 8px 0; border: 1px solid #e2e8f0; border-radius: 6px; }
    .item { padding: 6px 0; }
  </style>
</head>
<body>
  <nav id="sidebar">
    <div class="item">Home</div>
    <div class="item active">Settings</div>
  </nav>
  <main id="main">
    <div class="item active">Main active (ignored)</div>
  </main>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
  <script>
    $("#sidebar .item.active").css("fontWeight", "bold");
  </script>
</body>
</html>

Lines: 0 | Characters: 0

Live Preview Auto-refresh on Run

#sidebar .item.active — scoped query (Try It)