<script>
( function( $ ) {
    $( document ).ready( function() {
        function filterPath( string ) {
            return string
                .replace( /^\//, '' )
                .replace( /(index|default).[a-zA-Z]{3,4}$/, '' )
                .replace( /\/$/, '' );
        }

        var locationPath = filterPath( location.pathname );
        var scrollElem = scrollableElement( 'html', 'body' );

        // Any links with hash tags in them (can't do ^= because of fully qualified URL potential)
        $( 'a[href*=#]' ).each( function() {

            // Ensure it's a same-page link
            var thisPath = filterPath( this.pathname ) || locationPath;
            if ( locationPath == thisPath &&
                ( location.hostname == this.hostname || !this.hostname ) &&
                this.hash.replace( /#/, '' ) ) {

                // Ensure target exists
                var $target = $( this.hash ),
                    target = this.hash;
                if ( target ) {

                    // Find location of target
                    var targetOffset = $target.offset().top;
                    $( this ).click( function( event ) {

                        // Prevent jump-down
                        event.preventDefault();

                        // Animate to target
                        $( scrollElem ).animate( { scrollTop: targetOffset }, 400, function() {

                            // Set hash in URL after animation successful
                            location.hash = target;

                        } );
                    } );
                }
            }

        } );

        // Use the first element that is "scrollable" (cross-browser fix?)
        function scrollableElement( els ) {
            for ( var i = 0, argLength = arguments.length; i < argLength; i++ ) {
                var el = arguments,
                    $scrollElement = $( el );
                if ( $scrollElement.scrollTop() > 0 ) {
                    return el;
                } else {
                    $scrollElement.scrollTop( 1 );
                    var isScrollable = $scrollElement.scrollTop() > 0;
                    $scrollElement.scrollTop( 0 );
                    if ( isScrollable ) {
                        return el;
                    }
                }
            }
            return [];
        }
    } );
} )( jQuery );
</script>