ng-style in angularjs

<!DOCTYPE html>
<html>

<head>
  <style>
    .yelloColor {
      background-color: gray;
    }
    .meterColor {
      background-color: green;
    }
  </style>
  <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.15/angular.min.js"></script>
  <script>
    var app = angular.module('ngStyleApp', []);
    app.controller('ngStyleCtrl', function($scope) {
      $scope.bar = "48%";
    });
  </script>
</head>

<body ng-app="ngStyleApp" ng-controller="ngStyleCtrl">
  <div class="yelloColor">
    <div class="meterColor" ng-style="{'width':bar}">
      <h4> {{bar}} DATA USED OF 100%</h4>
    </div>
  </div>
</body>

</html>

// Code goes here

/* Styles go here */