nav.html

<nav class="navbar navbar-expand-lg bg-body-tertiary">
  <div class="container-fluid">
    <a class="navbar-brand" href="index.html">My Dua App</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarScroll" aria-controls="navbarScroll" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarScroll">
      <ul class="navbar-nav me-auto my-2 my-lg-0 navbar-nav-scroll" style="--bs-scroll-height: 100px;">
        <li class="nav-item">
          <a class="nav-link active" aria-current="page" href="index.html">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">
            Feelings
          </a>
          <ul class="dropdown-menu">
            <li><a class="dropdown-item" href="Angry.html">Angry</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>
        <li class="nav-item">
          <a class="nav-link disabled" aria-disabled="true">Link</a>
        </li>
      </ul>
      <form class="d-flex" role="search">
        <input class="form-control me-2" type="search" placeholder="Search" aria-label="Search">
        <button class="btn btn-outline-success" type="submit">Search</button>
      </form>
      <button id="themeToggle" class="btn btn-primary" style="margin-left: 10px;">
        <i id="themeIcon" class="fas fa-sun"></i>
      </button>
      
      <script>
        const themeToggleBtn = document.getElementById('themeToggle');
        const themeIcon = document.getElementById('themeIcon');
        const body = document.body;
    
        themeToggleBtn.addEventListener('click', () => {
        if (document.documentElement.getAttribute('data-bs-theme') == 'dark') {
            document.documentElement.setAttribute('data-bs-theme','light')
            themeIcon.classList.remove('fa-sun');
            themeIcon.classList.add('fa-moon');
        }
        else {
            document.documentElement.setAttribute('data-bs-theme','dark')
            themeIcon.classList.remove('fa-moon');
            themeIcon.classList.add('fa-sun');
        }
    });
      </script>



    </div>
  </div>
</nav>