Navbar занимает весь body?

Question

demon trigger @Core2Quad777

Bootstrap

Navbar занимает весь body?

Взял с бутстрапа оффканвас навбар. выглядит это все так:

<!DOCTYPE html>
<html lang="ru">
<head>
    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-9ndCyUaIbzAi2FUVXJi0CjmCapSmO7SnpJef0486qhLnuZ2cdeRhO02iuK6FUUVM" crossorigin="anonymous">
    <link rel = "stylesheet" href= "style.css"></link>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>???</title>
</head>
<body>
  <header>
    <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" aria-label="Toggle navigation">
          <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>
  </header>
  <main>
    <h1>Hello world!</h1>
  </main>
  <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/js/bootstrap.bundle.min.js" integrity="sha384-geWF76RCwLtnZ8qwWowPQNguL3RmwHVBC9FhGdlKrxdiJJigb/j/68SIy3Te4Bkz" crossorigin="anonymous"></script>
</body>
</html>

вот так выглядит полученная страница

и каким то образом, весь тег body попадает под этот навбар, т.е все остальное на странице как бы появляется, но закрывается этим навбаром.