How to change the init function of a theme?

[nasyxx]

Hi,

I want to derive the simlpe theme, and change some content of it to make my own theme. Because I only want to change some default global settings, I don't like to leave a copy in my local. Thus, I tried to change the default init function to inject the configuration. But it failed.

I tried to do like this:

#show: simple-theme.with(
  aspect-ratio: "16-9",
  config-methods(
    init: (self: none, body) => {
      set text(size: 25pt, font: "Andale Mono", fallback: true)

      show heading.where(level: 2): it => {
        text(bottom-edge: "bounds")[
          *#it.body*
          // #v(-30pt)
          #line(length: 100%, stroke: 2pt + gradient.linear(..color.map.mako))
          // #v(-20pt)
        ]
      }

      set math.equation(numbering: "(1)")

      show link: underline

      show strong: alert

      body
    },
  ),
)

= A

== BB

cccc

However, it shows the error:

error: panicked with: "Unsupported mark `touying-fn-wrapper` at page 2. You can't use it inside some functions like `context`. You may want to use the callback-style `uncover` function instead."
   ┌─ @preview/touying:0.5.3/src/configs.typ:48:8
   │
48 │         panic("Unsupported mark `" + kind + "` at page " + str(page-num) + ". You can't use it inside some functions like `context`. You may want to use the callback-style `uncover` function instead.")
   │         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Looks like I missed something.