change specific element style angular directive
/* AngularJS directives are extended HTML attributes with the prefix ng-.
* Lets you extend HTML with new attributes
* - The ng-app directive initializes an AngularJS application.
* - The ng-init directive initializes application data.
* - The ng-model directive binds the value of HTML controls (input, select, textarea)
* to application data
*/
<div ng-app="" ng-init="firstName='Javi'">
<p>Name: <input type="text" ng-model="firstName"></p>
<p>You wrote: {{ firstName }}</p>
</div>