Add option to include additional CSS files

Put additional CSS files in the static folder of your site and add the
filenames to config.toml in the css parameter.

See #13

README.md

@@ -96,6 +96,22 @@ The copyright message in the footer uses the name of the author of the site, as
     name = "Emiel"
 ```
 
+### Additional CSS files
+
+The theme can load additional CSS files for you, e.g. to override some of the styles, or the CSS that goes with a component that you're using. To add additional CSS files, put these files in the `static` folder of your site and add the `css` parameter to `config.toml`, like so:
+
+```
+[Params]
+css = ["custom.css"]
+```
+
+To load multiple CSS files, use the parameter like this:
+
+```
+[Params]
+css = ["custom.css", "custom2.css"]
+```
+
 ## Acknowledgments
 
 Thanks 

layouts/partials/head.html

@@ -22,6 +22,9 @@
 		{{- $style			:= resources.Get "scss/tale.scss" | toCSS $cssOptions }}
   		<link rel="stylesheet" href="{{ $style.RelPermalink }}">
 		<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Libre+Baskerville:400,400i,700">
+		{{ range .Site.Params.css -}}
+			<link rel="stylesheet" href="{{ . | relURL }}">
+		{{ end -}}
 
 		<!-- Favicon -->
 		<link rel="icon" type="image/png" sizes="32x32" href="{{ "images/favicon-32x32.png" | relURL }}">