اريد ان استخدم كود و تصميم جاهز من بوستراب لكنه لا يعمل يظهر هيكل من غير تصميم بوستراب هذا هو الكود 

<!DOCTYPE html>
<html lang="ar">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Navbar with Offcanvas</title>
    <!-- Bootstrap CSS -->
    <link href="https://stackpath.bootstrapcdn.com/bootstrap/5.3.0/css/bootstrap.min.css" rel="stylesheet">
    <!-- Custom CSS -->
    <link rel="stylesheet" href="styles.css">
</head>
<body>

<nav class="navbar navbar-dark bg-dark fixed-top">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Offcanvas dark navbar</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="offcanvas" data-bs-target="#offcanvasDarkNavbar" aria-controls="offcanvasDarkNavbar">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="offcanvas offcanvas-end text-bg-dark" tabindex="-1" id="offcanvasDarkNavbar" aria-labelledby="offcanvasDarkNavbarLabel">
      <div class="offcanvas-header">
        <h5 class="offcanvas-title" id="offcanvasDarkNavbarLabel">Dark offcanvas</h5>
        <button type="button" class="btn-close btn-close-white" data-bs-dismiss="offcanvas" aria-label="Close"></button>
      </div>
      <div class="offcanvas-body">
        <ul class="navbar-nav justify-content-end flex-grow-1 pe-3">
          <li class="nav-item">
            <a class="nav-link active" aria-current="page" href="#">Home</a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="#">Link</a>
          </li>
          <li class="nav-item dropdown">
            <a class="nav-link dropdown-toggle" href="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
              Dropdown
            </a>
            <ul class="dropdown-menu dropdown-menu-dark">
              <li><a class="dropdown-item" href="#">Action</a></li>
              <li><a class="dropdown-item" href="#">Another action</a></li>
              <li>
                <hr class="dropdown-divider">
              </li>
              <li><a class="dropdown-item" href="#">Something else here</a></li>
            </ul>
          </li>
        </ul>
        <form class="d-flex mt-3" role="search">
          <input class="form-control me-2" type="search" placeholder="Search" aria-label="Search">
          <button class="btn btn-success" type="submit">Search</button>
        </form>
      </div>
    </div>
  </div>
</nav>

<!-- Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/2.10.2/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/5.3.0/js/bootstrap.bundle.min.js"></script>

</body>
</html>

هذه صورة للتصميم بوستراب

و هذه رابط الصفحة اريد التصميم الموجود اسفل الصفحة