webviewprovider.js

var webviewProvider = (function() {
  if (/\/FBIOS/i.test(navigator.userAgent) === true) {
    return 'facebook';
  }
  if (/Twitter for/i.test(navigator.userAgent) === true) {
    return 'twitter';
  }
  if (/Pinterest\//.test(navigator.userAgent) === true) {
    return 'pinterest';
  }
  if (/\/\/t.co\//i.test(document.referrer) === true && /Safari\//.test(navigator.userAgent) === false) {
    return 'twitter';
  }
  if (/tumblr.com\//i.test(document.referrer) === true && /Safari\//.test(navigator.userAgent) === false) {
    return 'tumblr';
  }
  return null;
})();

if (webviewProvider !== null) {
  document.body.classList.add(webviewProvider);
}