It seems like this script doesn't support the customization feature for styles. Which for many is essential.
Also, just as importantly the wretched website now tries to install the newest version of stylish instead of installing the script. Even when I use this extension and click "download this style" I will be prompted to install it. (Which can easily be confused as a prompt to install the style, which one expects)
(The webextension version of the style is much inferior, so I won't use it.)