为什么我的引导按钮组看起来很有趣

Question

尝试让按钮组像引导页面上的按钮组一样工作。

HTML

        <div class="btn-group">
            <button class="btn btn-secondary" ng-class="{active: active_views[0]}" ng-click="changeView(0)">R-Theta</button>
            <button class="btn btn-secondary" ng-class="{active: active_views[1]}" ng-click="changeView(1)">Cartesian</button>
            <button class="btn btn-secondary" ng-class="{active: active_views[2]}" ng-click="changeView(2)">Longitudinal</button>
            <button class="btn btn-secondary" ng-class="{active: active_views[3]}" ng-click="">Console</button </div>
        </div>

结果

预期