btn-outline-

bootstrap5.css

.btn-outline-primary {
  color: #007bff;
  border-color: #007bff;
}

bootstrap5.css

.btn-outline-primary:hover {
  color: #fff;
  background-color: #007bff;
  border-color: #007bff;
}

bootstrap5.css

.btn-outline-primary:focus,
.btn-outline-primary.focus {
  box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.5);
}

bootstrap5.css

.btn-outline-primary.disabled,
.btn-outline-primary:disabled {
  color: #007bff;
  background-color: transparent;
}

bootstrap5.css

.btn-outline-primary:not(:disabled):not(.disabled):active,
.btn-outline-primary:not(:disabled):not(.disabled).active,
.show > .btn-outline-primary.dropdown-toggle {
  color: #fff;
  background-color: #007bff;
  border-color: #007bff;
}

bootstrap5.css

.btn-outline-primary:not(:disabled):not(.disabled):active:focus,
.btn-outline-primary:not(:disabled):not(.disabled).active:focus,
.show > .btn-outline-primary.dropdown-toggle:focus {
  box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.5);
}

bootstrap5.css

.btn-outline-secondary {
  color: #6c757d;
  border-color: #6c757d;
}

bootstrap5.css

.btn-outline-secondary:hover {
  color: #fff;
  background-color: #6c757d;
  border-color: #6c757d;
}

bootstrap5.css

.btn-outline-secondary:focus,
.btn-outline-secondary.focus {
  box-shadow: 0 0 0 0.2rem rgba(108, 117, 125, 0.5);
}

bootstrap5.css

.btn-outline-secondary.disabled,
.btn-outline-secondary:disabled {
  color: #6c757d;
  background-color: transparent;
}

bootstrap5.css

.btn-outline-secondary:not(:disabled):not(.disabled):active,
.btn-outline-secondary:not(:disabled):not(.disabled).active,
.show > .btn-outline-secondary.dropdown-toggle {
  color: #fff;
  background-color: #6c757d;
  border-color: #6c757d;
}

bootstrap5.css

.btn-outline-secondary:not(:disabled):not(.disabled):active:focus,
.btn-outline-secondary:not(:disabled):not(.disabled).active:focus,
.show > .btn-outline-secondary.dropdown-toggle:focus {
  box-shadow: 0 0 0 0.2rem rgba(108, 117, 125, 0.5);
}

bootstrap5.css

.btn-outline-success {
  color: #28a745;
  border-color: #28a745;
}

bootstrap5.css

.btn-outline-success:hover {
  color: #fff;
  background-color: #28a745;
  border-color: #28a745;
}

bootstrap5.css

.btn-outline-success:focus,
.btn-outline-success.focus {
  box-shadow: 0 0 0 0.2rem rgba(40, 167, 69, 0.5);
}

bootstrap5.css

.btn-outline-success.disabled,
.btn-outline-success:disabled {
  color: #28a745;
  background-color: transparent;
}

bootstrap5.css

.btn-outline-success:not(:disabled):not(.disabled):active,
.btn-outline-success:not(:disabled):not(.disabled).active,
.show > .btn-outline-success.dropdown-toggle {
  color: #fff;
  background-color: #28a745;
  border-color: #28a745;
}

bootstrap5.css

.btn-outline-success:not(:disabled):not(.disabled):active:focus,
.btn-outline-success:not(:disabled):not(.disabled).active:focus,
.show > .btn-outline-success.dropdown-toggle:focus {
  box-shadow: 0 0 0 0.2rem rgba(40, 167, 69, 0.5);
}

bootstrap5.css

.btn-outline-info {
  color: #17a2b8;
  border-color: #17a2b8;
}

bootstrap5.css

.btn-outline-info:hover {
  color: #fff;
  background-color: #17a2b8;
  border-color: #17a2b8;
}

bootstrap5.css

.btn-outline-info:focus,
.btn-outline-info.focus {
  box-shadow: 0 0 0 0.2rem rgba(23, 162, 184, 0.5);
}

bootstrap5.css

.btn-outline-info.disabled,
.btn-outline-info:disabled {
  color: #17a2b8;
  background-color: transparent;
}

bootstrap5.css

.btn-outline-info:not(:disabled):not(.disabled):active,
.btn-outline-info:not(:disabled):not(.disabled).active,
.show > .btn-outline-info.dropdown-toggle {
  color: #fff;
  background-color: #17a2b8;
  border-color: #17a2b8;
}

bootstrap5.css

.btn-outline-info:not(:disabled):not(.disabled):active:focus,
.btn-outline-info:not(:disabled):not(.disabled).active:focus,
.show > .btn-outline-info.dropdown-toggle:focus {
  box-shadow: 0 0 0 0.2rem rgba(23, 162, 184, 0.5);
}

bootstrap5.css

.btn-outline-warning {
  color: #ffc107;
  border-color: #ffc107;
}

bootstrap5.css

.btn-outline-warning:hover {
  color: #212529;
  background-color: #ffc107;
  border-color: #ffc107;
}

bootstrap5.css

.btn-outline-warning:focus,
.btn-outline-warning.focus {
  box-shadow: 0 0 0 0.2rem rgba(255, 193, 7, 0.5);
}

bootstrap5.css

.btn-outline-warning.disabled,
.btn-outline-warning:disabled {
  color: #ffc107;
  background-color: transparent;
}

bootstrap5.css

.btn-outline-warning:not(:disabled):not(.disabled):active,
.btn-outline-warning:not(:disabled):not(.disabled).active,
.show > .btn-outline-warning.dropdown-toggle {
  color: #212529;
  background-color: #ffc107;
  border-color: #ffc107;
}

bootstrap5.css

.btn-outline-warning:not(:disabled):not(.disabled):active:focus,
.btn-outline-warning:not(:disabled):not(.disabled).active:focus,
.show > .btn-outline-warning.dropdown-toggle:focus {
  box-shadow: 0 0 0 0.2rem rgba(255, 193, 7, 0.5);
}

bootstrap5.css

.btn-outline-danger {
  color: #dc3545;
  border-color: #dc3545;
}

bootstrap5.css

.btn-outline-danger:hover {
  color: #fff;
  background-color: #dc3545;
  border-color: #dc3545;
}

bootstrap5.css

.btn-outline-danger:focus,
.btn-outline-danger.focus {
  box-shadow: 0 0 0 0.2rem rgba(220, 53, 69, 0.5);
}

bootstrap5.css

.btn-outline-danger.disabled,
.btn-outline-danger:disabled {
  color: #dc3545;
  background-color: transparent;
}

bootstrap5.css

.btn-outline-danger:not(:disabled):not(.disabled):active,
.btn-outline-danger:not(:disabled):not(.disabled).active,
.show > .btn-outline-danger.dropdown-toggle {
  color: #fff;
  background-color: #dc3545;
  border-color: #dc3545;
}

bootstrap5.css

.btn-outline-danger:not(:disabled):not(.disabled):active:focus,
.btn-outline-danger:not(:disabled):not(.disabled).active:focus,
.show > .btn-outline-danger.dropdown-toggle:focus {
  box-shadow: 0 0 0 0.2rem rgba(220, 53, 69, 0.5);
}

bootstrap5.css

.btn-outline-light {
  color: #f8f9fa;
  border-color: #f8f9fa;
}

bootstrap5.css

.btn-outline-light:hover {
  color: #212529;
  background-color: #f8f9fa;
  border-color: #f8f9fa;
}

bootstrap5.css

.btn-outline-light:focus,
.btn-outline-light.focus {
  box-shadow: 0 0 0 0.2rem rgba(248, 249, 250, 0.5);
}

bootstrap5.css

.btn-outline-light.disabled,
.btn-outline-light:disabled {
  color: #f8f9fa;
  background-color: transparent;
}

bootstrap5.css

.btn-outline-light:not(:disabled):not(.disabled):active,
.btn-outline-light:not(:disabled):not(.disabled).active,
.show > .btn-outline-light.dropdown-toggle {
  color: #212529;
  background-color: #f8f9fa;
  border-color: #f8f9fa;
}

bootstrap5.css

.btn-outline-light:not(:disabled):not(.disabled):active:focus,
.btn-outline-light:not(:disabled):not(.disabled).active:focus,
.show > .btn-outline-light.dropdown-toggle:focus {
  box-shadow: 0 0 0 0.2rem rgba(248, 249, 250, 0.5);
}

bootstrap5.css

.btn-outline-dark {
  color: #343a40;
  border-color: #343a40;
}

bootstrap5.css

.btn-outline-dark:hover {
  color: #fff;
  background-color: #343a40;
  border-color: #343a40;
}

bootstrap5.css

.btn-outline-dark:focus,
.btn-outline-dark.focus {
  box-shadow: 0 0 0 0.2rem rgba(52, 58, 64, 0.5);
}

bootstrap5.css

.btn-outline-dark.disabled,
.btn-outline-dark:disabled {
  color: #343a40;
  background-color: transparent;
}

bootstrap5.css

.btn-outline-dark:not(:disabled):not(.disabled):active,
.btn-outline-dark:not(:disabled):not(.disabled).active,
.show > .btn-outline-dark.dropdown-toggle {
  color: #fff;
  background-color: #343a40;
  border-color: #343a40;
}

bootstrap5.css

.btn-outline-dark:not(:disabled):not(.disabled):active:focus,
.btn-outline-dark:not(:disabled):not(.disabled).active:focus,
.show > .btn-outline-dark.dropdown-toggle:focus {
  box-shadow: 0 0 0 0.2rem rgba(52, 58, 64, 0.5);
}

html bootstrap5 Sample

アウトラインボタンの色：btn-outline-*

  <!-- 塗りつぶしがない -->
  <button class="btn btn-outline-primary">outline-primary</button>
  <button class="btn btn-outline-secondary">outline-secondary</button>
  <button class="btn btn-outline-success">outline-success</button>
  <button class="btn btn-outline-danger">outline-danger</button>
  <button class="btn btn-outline-warning">outline-warning</button>
  <button class="btn btn-outline-info">outline-info</button>
  <button class="btn btn-outline-light">outline-light</button>
  <button class="btn btn-outline-dark">outline-dark</button>

ナビバーのデザイン：navbar-darkとbg-dark

  <nav class="navbar navbar-expand-lg navbar-dark bg-dark">
    <a class="navbar-brand" href="#">ブランド</a>
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav"
      aria-controls="navbarNav" 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="navbarNav">
      <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>
      <!-- アウトラインの検索ボタン、darkだど映える -->
      <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-info my-2 my-sm-0" type="submit">検索</button>
      </form>
    </div>
  </nav>

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>