andead

$form['#validate'][] = 'Drupal\mytheme\AjaxCommentForm::ajaxValidateCallback';

$attachment = array(
  'filepath' => 'README.txt'
);
drupal_mail('system', 'mail', 'mail@gmail.com', language_default(), array(
  'context' => array(
    'subject' => 'Some subject',
    'message' => 'Some message',
  ),
  'attachments' => array($attachment),
));

@each $key, $color in $colors {
    $index: index($colors, $color);
    .test-#{$index}-#{$key} {
        color: $color;
    }
}

.btn,
.obr {
  display:block;
  @at-root {
    .btn {
      font-size: 24px;
    }
  }
}