I will post the code next days after I will clean it a bit, maybe I'll have time to save the css files and js files on the ESP itself, now, to have the web interface styled like you seen in the screenshot, in the HTML code the ESP sends to the borowser I have a few external links hosted on one of my hosting servers, so , if the ESP is not setup to connect to a router with internet access, the interface will not be so nice, this is why I wanted to use FS Browser or other options .. to save the css and js files in the ESP. Hope this won;t slow the browsing too much.
I tryied to have as much of the interface rendered on the browser side (desktop pc, smartphone, tablet) and not on the server side (ESP) .. all the graphs are made using svg so everything is rendered in the browser, there's no file sent by the ESP for all the graphs, also for the icons I used FontAwesome, it's just a font with hundreds of nice icons, so there is just one request for the font file and in the web interface I can display as many icons I want.