A method of display modification in a client server web system, comprising, intercepting, by a web intermediary, a response to a client request, sent by a server in response to the request, the response including client side active content adapted to execute at a browsing software on a client computer; replacing at least one display-related code section in said response by a wrapper section that includes code for modification of at least one display element and code for executing the original display-related code section; and executing said wrapper section as client side active content at said client to generate a display, modified from a display that would have been generated by executing the response.