Twitter share button as AngularJS directive.

directives.js

directives.directive('twitter', [
    function() {
        return {
            link: function(scope, element, attr) {
                setTimeout(function() {
                        twttr.widgets.createShareButton(
                            attr.url,
                            element[0],
                            function(el) {}, {
                                count: 'none',
                                text: attr.text
                            }
                        );
                });
            }
        }
    }
]);

index.html

<script src="http://platform.twitter.com/widgets.js"></script>

<a twitter data-text="Your text: {{file.name}}" data-url="http://127.0.0.1:3000/{{file.link}}"></a>

How can I change the style of the button?