Adding a CDN asset to drupal theme

Add CDN/External css

  <?php /* Comment goes here */
 function beginning_preprocess_html(&$variables) {  drupal_add_css('https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css', array('type' => 'external'));
}
?>

Add CDN/External JS

  <?php /** * Comment goes here */
/*
 * Without any preprocess hook
 */
drupal_add_js('//maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js', array(
  'type' => 'external',
  'scope' => 'header',
  'group' => JS_THEME,
  'every_page' => TRUE,
  'weight' => -1,
));
?> 

Sample blackbox block

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Maecenas non porta odio, id mattis erat.

Nam sed tincidunt eros. Donec a venenatis odio, vitae commodo sem. Vivamus ullamcorper pellentesque erat, in adipiscing tortor scelerisque sit amet. Nulla pulvinar urna magna. Vivamus a ipsum lorem. Etiam adipiscing pulvinar lorem.