Breakage: Custom theme builds fail now when compiling the dark theme.

[Datseris]

Hello, the documentation builds for JuliaDynamics are no suddenly failing with the message ERROR: LoadError: Undefined variable: "$todo".. This error occurs when we try to compile our own theme. It occurs when we call Themes.compile for the dark theme. The script we run to compile the theme is this one: https://github.com/JuliaDynamics/doctheme/blob/master/build_docs_with_style.jl . A stack trace can be found here for example: https://github.com/JuliaDynamics/PeriodicOrbits.jl/actions/runs/10847716300/job/30103351759?pr=3#step:5:8 .

Some (unknowingly) breaking change in documenter themeing triggers this now.

The reason I believe that this is a Documenter.jl problem is that there is no $todo in the whole repo that has the doc theme, nor in the repo that the docs are build for.
This is where the error is coming from:

Documenter.jl/assets/html/scss/documenter-dark.scss

Line 35 in a0257f9

$todo: $purple;

We don't re-color any admonitions in our theme, so I don't really understand why the $todo admonition is the one that errors.