btn btn-primary btn-lg active
html bootstrap5 Sample
アクティブ状態のボタン：active
<a href="#" class="btn btn-primary btn-lg active" role="button" aria-pressed="true">アクティブボタン</a>
<a href="#" class="btn btn-primary btn-lg" role="button">通常ボタン</a>
<a href="#" class="btn btn-primary btn-lg active" role="button" aria-pressed="true">アクティブボタン</a>
<a href="#" class="btn btn-primary btn-lg" role="button">通常ボタン</a>