feat(themes): add desktopBackground prop to all themes (#238)

* feat(themes): map Windows theme Background to desktopBackground theme prop

* feat(themes): add desktopBackground prop to themes by tPenguinLTG

* feat(themes): add desktopBackground prop to Windows-inspired themes

Use colors from original Windows theme.

* feat(themes): add desktopBackground prop to all other themes

Use placeholder #008080 (teal) until more background colours are designed.

* feat(themes): add desktopBackground prop to docz default theme

* feat(themes): use desktopBackground theme prop where appropriate

Create a styled Wrapper component that consumes the theme and uses the
desktopBackground prop.

Author: tpenguinltg

src/AppBar/AppBar.stories.js

@@ -1,4 +1,5 @@
 import React from 'react';
+import styled from 'styled-components';
 import {
   AppBar,
   Toolbar,
@@ -13,19 +14,12 @@ import logoIMG from '../assets/images/logo.png';
 export default {
   title: 'AppBar',
   component: AppBar,
-  decorators: [
-    story => (
-      <div
-        style={{
-          padding: '5rem',
-          background: 'teal'
-        }}
-      >
-        {story()}
-      </div>
-    )
-  ]
+  decorators: [story => <Wrapper>{story()}</Wrapper>]
 };
+const Wrapper = styled.div`
+  padding: 5rem;
+  background: ${({ theme }) => theme.desktopBackground};
+`;
 
 export const Default = () => {
   const [open, setOpen] = React.useState(false);

src/Bar/Bar.stories.js

@@ -1,23 +1,17 @@
 import React from 'react';
+import styled from 'styled-components';
 
 import { Bar, AppBar, Toolbar, Button } from 'react95';
 
 export default {
   title: 'Bar',
   component: Bar,
-  decorators: [
-    story => (
-      <div
-        style={{
-          padding: '5rem',
-          background: 'teal'
-        }}
-      >
-        {story()}
-      </div>
-    )
-  ]
+  decorators: [story => <Wrapper>{story()}</Wrapper>]
 };
+const Wrapper = styled.div`
+  padding: 5rem;
+  background: ${({ theme }) => theme.desktopBackground};
+`;
 
 export const Default = () => (
   <AppBar>