navbar-light

bootstrap5.css

.navbar-light .navbar-brand {
  color: rgba(0, 0, 0, 0.9);
}

bootstrap5.css

.navbar-light .navbar-brand:hover,
.navbar-light .navbar-brand:focus {
  color: rgba(0, 0, 0, 0.9);
}

bootstrap5.css

.navbar-light .navbar-nav .nav-link {
  color: rgba(0, 0, 0, 0.5);
}

bootstrap5.css

.navbar-light .navbar-nav .nav-link:hover,
.navbar-light .navbar-nav .nav-link:focus {
  color: rgba(0, 0, 0, 0.7);
}

bootstrap5.css

.navbar-light .navbar-nav .nav-link.disabled {
  color: rgba(0, 0, 0, 0.3);
}

bootstrap5.css

.navbar-light .navbar-nav .show > .nav-link,
.navbar-light .navbar-nav .active > .nav-link,
.navbar-light .navbar-nav .nav-link.show,
.navbar-light .navbar-nav .nav-link.active {
  color: rgba(0, 0, 0, 0.9);
}

bootstrap5.css

.navbar-light .navbar-toggler {
  color: rgba(0, 0, 0, 0.5);
  border-color: rgba(0, 0, 0, 0.1);
}

bootstrap5.css

.navbar-light .navbar-text {
  color: rgba(0, 0, 0, 0.5);
}

bootstrap5.css

.navbar-light .navbar-text a {
  color: rgba(0, 0, 0, 0.9);
}

bootstrap5.css

.navbar-light .navbar-text a:hover,
.navbar-light .navbar-text a:focus {
  color: rgba(0, 0, 0, 0.9);
}

html bootstrap5 Sample

navbar-lightで文字色を暗くし、背景色をCSSで設定

  <nav class="navbar navbar-expand-lg navbar-light" style="background-color: #e3f2fd;">
    <a class="navbar-brand" href="#">ブランド</a>
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent3"
      aria-controls="navbarSupportedContent3" aria-expanded="false" aria-label="ナビゲーション切替">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarSupportedContent3">
      <ul class="navbar-nav mr-auto">
        <li class="nav-item"><a class="nav-link" href="#">リンク1</a></li>
        <li class="nav-item"><a class="nav-link" href="#">リンク2</a></li>
        <li class="nav-item"><a class="nav-link" href="#">リンク3</a></li>
      </ul>
      <form class="form-inline my-2 my-lg-0">
        <input class="form-control mr-sm-2" type="search" placeholder="検索" aria-label="検索">
        <button class="btn btn-outline-primary my-2 my-sm-0" type="submit">検索</button>
      </form>
    </div>
  </nav>