按钮</button>
                        <button type="button" class="btn btn-default">默认按钮</button>
                        <br/>
                        <button type="button" class="btn btn-primary btn-sm">小按钮</button>
                        <button type="button" class="btn btn-default btn-sm">小按钮</button>
                        <br/>
                        <button type="button" class="btn btn-primary btn-xs">Mini按钮</button>
                        <button type="button" cl