Change: Allow sites to use local Sass files

This processes ".scss" files in the "assets/css" directory, allowing
downstream sites to use Sass as well as plain CSS.

doc/content/getstarted.md

@@ -46,7 +46,7 @@ Run `make html`. Output appears in `./public`.
 
 Edit `config.yaml` to your liking.
 
-To customize styling, add one or more `*.css` files to the `assets/css` directory.
+To customize styling, add one or more `*.css` (or `*.scss` for Sass) files to the `assets/css` directory.
 These files may make use of Hugo templating,
 e.g. to access configuration variables as `{{ .Site.Params.somevar }}`.
 

layouts/partials/css.html

@@ -2,7 +2,7 @@
 {{- $page := . -}}
 
 {{- $inServerMode := .Site.IsServer -}}
-{{- $sass         := (slice "theme-css/fresh/core.scss") -}}
+{{- $sass         := (slice "theme-css/fresh/core.scss") | append (resources.Match "css/*.scss") -}}
 {{- $cssOpts      := cond ($inServerMode) (dict "enableSourceMap" true) (dict "outputStyle" "compressed") -}}
 
 <!-- Fonts -->
@@ -15,7 +15,7 @@
 <link rel="stylesheet" href="{{ $fontUrl }}">
 <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bulma@0.9.4/css/bulma.min.css">
 
-<!-- SASS --- currently only for fresh -->
+<!-- SASS -->
 {{- range $sass -}}
 
 {{- if $inServerMode -}}