Q: Can I add custom GUI elements? Like calculators?

A: Sure, you can use the plugin type supported by Booktorio, but remember that Booktorio is designed to create wikis, so all interfaces are meant to be stateless, don't use plugins to create GUI elements that must remain loaded in times, don't create plugin functions that have problem to run two time in the same savegame/map.

Q: How can I give to Booktorio my GUI styles?

A: All GUI style must be defined in the standard Factorio table for the styles (also in the standard specification):

data.raw["gui-style"]["default"]

With a proper indexed name, for example:

data.raw["gui-style"]["default"]["bk-wiki-description-label"] =
{
    type = "label_style",
    parent = "label",
    font = "default",
    rich_text_setting = "enabled",
    single_line = false,
    padding = 1,
    margin = 1
}

the name "bk-wiki-description-label" is the name that identify the style, and is the string that Booktorio require to apply the style.