Allow for custom icons and colour schemes

[zkamvar]

Right now we have a set of four colour schemes and logos based on our curricula. Of course, there are other organisations that use our infrastructure and would probably like to not have to create a new fork of varnish in order to use a different logo or colour scheme. Thus:

• create yaml item that can point to a logo/favicon file/s to replace the existing logo/favicon.
• create yaml item that can override some of the colorschemes (this may require modification of the scss directly, which would mean that varnish needs this as well)

[zkamvar]

N.B. This is very related to #66

[RaoOfPhysics]

Thanks for the lovely and useful package, @zkamvar, and thanks also for thinking about reuse of the template beyond The Carpentries!

I was wondering if you could also add “favicon” to the list of customisation options, as a the moment it seems like that’s hard-coded as well. (EDIT: Oh, and the footer too! See https://learntodiscover.github.io/lesson2_sandpaper/ and https://contributor.r-project.org/r-bug-tracking-lesson/ for example.)

Many thanks, once again!

[zkamvar]

I was wondering if you could also add “favicon” to the list of customisation options, as a the moment it seems like that’s hard-coded as well.

Of course! It's something that may take some time to get going since there are a few moving parts that dictate these (for example, see modifications in sandpaper and modifications in varnish needed to update the theme (note that Saba had to add a python and PDF engine to her version of sandpaper, so there's a lot more to her changes than styling)).

Right now, I've painted myself into a corner by building the source into the minified version before the package is built. This means that the colours are hard-coded in the CSS. The icons are a bit more flexible since I have the carpentry variable that controls them, but it's still a bit of a challenge.

In the meantime, one workaround that should work is:

1. fork the varnish repository
2. change the colours in https://github.com/carpentries/varnish/blob/main/source/stylesheets/variables.scss
3. change carpentries-logo.svg and carpentries-logo-sm.svg to use your logo.
4. add varnish: r-devel/varnish to your config file to use this version of varnish on your site.

The logo and colors are things I'm unlikely to change in varnish (until I work out the right path to allow for customisation), so you can keep up-to-date by merging and the github actions will regenerate the minified CSS once it gets to the main branch.

[RaoOfPhysics]

Sounds ace! Thanks for documenting the alternative options. :)