I have added support for gzipping the static css, js, html files, which helps both with saving flash space and both bandwidth if dealing with large static text files. The feature can be enabled/disabeld in the Makefile. If enabled it gzips the js/css/html files and the webserver code also sends the Content-Encoding: gzip header if enabled.
BTW. what version of esptool do you use?
The command line arguments in the Makefile does not seems to be the same what is used by this esptool:
https://github.com/themadinventor/esptool
Thank you for your work on esp-httpd, it is a very useful project for me!