JSFiddle - React, Tailwind, and code Playground

HTML

<div ng-app="organHome">
<dl class="sub-nav" ng-controller="inModalSwitchCtrl">
 <dd class="bold"><a ng-click="toggleBold()">Contents</a></dd>
 <dd><a ng-click="toggleBold()">Comments</a></dd>
</dl>
</div>

CSS

.bold {font-weight: bold}

JavaScript

angular.module('organHome', [])

  .controller('inModalSwitchCtrl', function ($scope) {
     
      $scope.toggleBold = function() {
          angular.element(document).find('dd').toggleClass('bold');
      };
  });