bootstrap4.css
button,
[type="button"],
[type="reset"],
[type="submit"] {
  -webkit-appearance: button;
}
bootstrap4.css
button:not(:disabled),
[type="button"]:not(:disabled),
[type="reset"]:not(:disabled),
[type="submit"]:not(:disabled) {
  cursor: pointer;
}
bootstrap4.css
button::-moz-focus-inner,
[type="button"]::-moz-focus-inner,
[type="reset"]::-moz-focus-inner,
[type="submit"]::-moz-focus-inner {
  padding: 0;
  border-style: none;
}
bootstrap4.css
input[type="submit"].btn-block,
input[type="reset"].btn-block,
input[type="button"].btn-block {
  width: 100%;
}
bootstrap4.css
.text-reset {
  color: inherit !important;
}
■ボタン:button:コンポーネント:a要素やinput要素でボタンを作成する

  <a class="btn btn-primary" href="#" role="button">a要素ボタン</a>
  <input class="btn btn-primary" type="button" value="inputボタン">
  <input class="btn btn-primary" type="submit" value="submitボタン">
  <input class="btn btn-primary" type="reset" value="resetボタン">