Extend application Sass for unbranded Sass

Ensures all the same features are avaliable, for example tasks lists and step by steps.

app/assets/sass/unbranded-ie8.scss

@@ -0,0 +1,3 @@
+$govuk-is-ie8: true;
+
+@import "unbranded";

app/assets/sass/unbranded.scss

@@ -1,24 +1,16 @@
 // The unbranded stylesheet is used if you need to create pages in your
 // prototype without the GOV.UK branding.
 //
-// See localhost:3000/docs/examples/blank-unbranded
+// See localhost:3000/docs/templates/blank-unbranded
 
-// Import colour palette and applied colours so that we can use
-// $govuk-body-background-colour in our overrides below.
-// 
-// If you need to enable compatibility mode or the legacy palette, do that
-// *before* these imports.
-@import "node_modules/govuk-frontend/govuk/settings/colours-palette";
-@import "node_modules/govuk-frontend/govuk/settings/colours-applied";
+// Import settings first so we can override them before importing all of GOV.UK Frontend
+// If you need to enable compatibility mode or the legacy palette, do that *before* this import.
+@import "node_modules/govuk-frontend/govuk/settings/all";
 
-// Style links and paragraphs by default
-$govuk-global-styles: true;
-
-// Override the govuk-frontend font stack
+// Override the default GOV.UK Frontend font stack
 $govuk-font-family: "HelveticaNeue", "Helvetica Neue", "Arial", "Helvetica", sans-serif;
 
-// Override the canvas background colour, which is normally grey to blend with
-// the GOV.UK footer.
+// Override the canvas background colour, which is normally grey to blend with the GOV.UK footer.
 $govuk-canvas-background-colour: $govuk-body-background-colour;
 
-@import "node_modules/govuk-frontend/govuk/all";
+@import "application";