Add modules for headings in the styleguide

The CSS reset removed default browser styles for h1, h2, h3, etc elements,
resulting in a pretty weird looking styleguide. This adds modules for headings,
one version for use with plain Html, the other for use with Html.Styled.

styleguide-app/Headings.elm

@@ -0,0 +1,38 @@
+module Headings exposing (h1, h2, h3, h4, h5)
+
+import HeadingsStyled
+import Html
+import Html.Styled
+
+
+h1 : List (Html.Html msg) -> Html.Html msg
+h1 =
+    toRootHtml HeadingsStyled.h1
+
+
+h2 : List (Html.Html msg) -> Html.Html msg
+h2 =
+    toRootHtml HeadingsStyled.h2
+
+
+h3 : List (Html.Html msg) -> Html.Html msg
+h3 =
+    toRootHtml HeadingsStyled.h3
+
+
+h4 : List (Html.Html msg) -> Html.Html msg
+h4 =
+    toRootHtml HeadingsStyled.h4
+
+
+h5 : List (Html.Html msg) -> Html.Html msg
+h5 =
+    toRootHtml HeadingsStyled.h5
+
+
+toRootHtml : (List (Html.Styled.Html msg) -> Html.Styled.Html msg) -> (List (Html.Html msg) -> Html.Html msg)
+toRootHtml node =
+    \children ->
+        List.map Html.Styled.fromUnstyled children
+            |> node
+            |> Html.Styled.toUnstyled

styleguide-app/HeadingsStyled.elm

@@ -0,0 +1,29 @@
+module HeadingsStyled exposing (h1, h2, h3, h4, h5)
+
+import Html.Styled exposing (Html)
+import Nri.Ui.Text.V2 as Text
+
+
+h1 : List (Html msg) -> Html msg
+h1 =
+    Text.heading
+
+
+h2 : List (Html msg) -> Html msg
+h2 =
+    Text.heading
+
+
+h3 : List (Html msg) -> Html msg
+h3 =
+    Text.subHeading
+
+
+h4 : List (Html msg) -> Html msg
+h4 =
+    Text.subHeading
+
+
+h5 : List (Html msg) -> Html msg
+h5 =
+    Text.subHeading