A simple visual editor script in php with saving to a file?

Question

CMS

Task : in the public folder is index.html. The script is in the admin folder. The script should be able to ask for a password, load the /public/index.html file, display it as html (along with html and head) and in visual mode be able to do something like ckeditor, etc.. By clicking on the "save" button - save the result to the index.html file.
Something like the simplest cms. The main thing is ease of installation, minimum requirements (size, dependencies), of course, authentication (albeit basic http)
Goal : make a template and if the client wants to take it for himself, then provide basic customization (with easy access to html), minimum requirements for hosting.
I am not very familiar with PHP (more - ruby, js), but I tend to it, because support is much easier and cheaper.
Of these solutions, I had a glimpse of sitecake, ckeditor. It seems to be "it", but the size of the sitecake seemed large (5 MB). Not much for hosting, of course, but my perfectionism infringes, because it seems that the task can be solved easier by removing the excess).
I would be grateful for advice, comments, presentation of alternative options.
PS
As a very cool bonus, I would like, for example, an inline "insertion" of a picture into the background (for example, click on a block, select a picture and it will be our background, we can also add all the necessary background properties there)
Interested in living and developing projects or enthusiasm to make a very simple user editing system.
just for fan at the moment it is interesting to make it possible to add css (possibly js) inline and collect, minify, optimize them on the server (god mode), a la dreamweaver online service + static hosting + site builder from blocks that can add [ or sell] other developers for regular users (in the distant future in a perfect world)
PSS
Sorry if the dreams in the PS block took up a lot of your time. Thanks

Answer 1

I recommend Simple Visual Editor 2015.

Answer 2

There are no ready-made solutions specifically for your task. It is unlikely that someone will undertake to carry it out, after all, this is not a freelance exchange .