/**

 * Makes "skip to content" link work correctly in IE9, Chrome, and Opera

 * for better accessibility.

 *

 * @link http://www.nczonline.net/blog/2013/01/15/fixing-skip-to-content-links/

 */

 ( function() {

	var isWebkit = navigator.userAgent.toLowerCase().indexOf( 'webkit' ) > -1,

		isOpera  = navigator.userAgent.toLowerCase().indexOf( 'opera' )  > -1,

		isIE     = navigator.userAgent.toLowerCase().indexOf( 'msie' )   > -1;

	if ( ( isWebkit || isOpera || isIE ) && document.getElementById && window.addEventListener ) {

		window.addEventListener( 'hashchange', function() {

			var id = location.hash.substring( 1 ),

				element;

			if ( ! ( /^[A-z0-9_-]+$/.test( id ) ) ) {

				return;

			}

			element = document.getElementById( id );

			if ( element ) {

				if ( ! ( /^(?:a|select|input|button|textarea)$/i.test( element.tagName ) ) ) {

					element.tabIndex = -1;

				}

				element.focus();

				// Repositions the window on jump-to-anchor to account for admin bar and border height.

				window.scrollBy( 0, -53 );

			}

		}, false );

	}

} )();