HoloViews Colorbar not styled for dark themed template

[MarcSkovMadsen]

Panel: 0.12.4

The ColorBar is unreadable when using the FastListTemplate with the dark theme.

I would like this to work for an example I am contributing to the scikit-image docs.

import holoviews as hv
import panel as pn
from skimage import data, filters

image = data.coins()
edges = filters.sobel(image)*256
bounds = (-1, -1, 1, 1)

after_img = hv.Image(edges, bounds=bounds).apply.opts(
    cmap="binary_r", responsive=True, title="After", active_tools=["box_zoom"], tools=["hover"], colorbar=True
)

layout=pn.panel(after_img, height=800, aspect_ratio=1)

pn.template.FastListTemplate(
    site="Panel and Scikit-Image",
    main=[layout],
    header_background="#292929",
    theme="dark",
).servable()

How do I fix this?

I would like to contribute a PR. I assume I would have to update the Bokeh Theme generation here

panel/panel/template/fast/theme.py

Line 62 in 396ce2f

return {

.

I can now see that I need to change to