{
                        span.style.color = 'grey';
                    }

                    owner.appendChild(span);
                }

                diff.forEach(function (part) {
                    if (part.added) {
                        add_diff_span_to(right, 'added', part.value);
                    } else if (part.removed) {
                        add_diff_span_to(left, 'removed', part.value);
                    }
                    else {
                        add_diff_span_to(left,  'k