Ng-Style

<!DOCTYPE html>
<html lang="en-US">
<head>
 <title>Welcome in the Angular JS</title>
 <script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.4.0-rc.1/angular.min.js"></script>
</head>
<body ng-app>
  <div>
    <button ng-click="msgStyle={'color':'#5cb85c'}">Success Message</button>
    <button ng-click="msgStyle={'color':'#d9534f'}">Danger Message</button>
    <button ng-click="msgStyle={'color':'#5bc0de'}">Info Message</button>
    <button ng-click="msgStyle={'color':'#f0ad4e'}">Warning Message</button>
    <h1 ng-style="msgStyle">Hi! Reagan.</h1>
  </div>
</body>
</html>
Output