Angular: Empty Fiddle

http://angularjs.org/

HTML

<script src="http://code.angularjs.org/angular-1.0.1.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<br />
<div ng-app ng-controller="MyCtrl" class='container'>
<fieldset>
<legend>Two Group</legend>
  <input type="text" 
      ng-model="model.First" 
      ng-required="!model.Last" 
      class='form-control'/>
<br/>
<input type="text" 
      ng-model="model.Last"
      ng-required="!model.First"  
      class='form-control'/>
</fieldset>

<legend>Three Group</legend>
  <input type="text" 
      ng-model="fields.one" 
      ng-required="!(fields.two || fields.three)" 
      class='form-control' />
<br/>
<input type="text" 
      ng-model="fields.two"
      ng-required="!(fields.one || fields.three)" 
      class='form-control' />
<br/>
<input type="text" 
      ng-model="fields.three" 
      ng-required="!(fields.one|| fields.two)" 
      class='form-control' />
</fieldset>
</div>

CSS

.ng-invalid-required{
  border-left: 5px solid #990000;
}

.ng-valid-required{
  border-left: 5px solid #009900;
}

legend {
    width:inherit; 
    padding:0 10px; 
    left and right */
    border: 2px solid #333;
}

JavaScript

var myApp = angular.module('myApp',[]);

//myApp.directive('myDirective', function() {});
//myApp.factory('myService', function() {});

function MyCtrl($scope) {
    $scope.name = 'Superhero';
}