bootstrap4 基本按钮样式

<button type="button" class="btn">基本按钮</button>

<button type="button" class="btn btn-primary">主要按钮</button>

<button type="button" class="btn btn-secondary">次要按钮</button>

<button type="button" class="btn btn-success">成功</button>

<button type="button" class="btn btn-info">信息</button>

<button type="button" class="btn btn-warning">警告</button>

<button type="button" class="btn btn-danger">危险</button>

<button type="button" class="btn btn-dark">黑色</button>

<button type="button" class="btn btn-light">浅色</button>

<button type="button" class="btn btn-link">链接</button>