fix: Ensure PostCSS processing actually happens

layouts/_default/baseof.html

@@ -8,7 +8,8 @@
       <meta name="description" content="{{ . }}" />
     {{ end }}
     <title>{{ .Title }} - {{ .Site.Title }}</title>
-    {{ $twbssass := resources.Get "styles/mix-twbs.scss" | resources.ToCSS | minify | resources.PostProcess }}
+    {{ $twbssass := resources.Get "styles/mix-twbs.scss" }}
+    {{ $twbssass = $twbssass | resources.ToCSS | resources.PostCSS | minify | resources.PostProcess }}
     <link href="{{ $twbssass.RelPermalink }}" rel="stylesheet" />
   </head>