Remove old fill-canvas theme preview technique

src/components/button/button.stories.mdx

@@ -1,7 +1,6 @@
 import { Story, Canvas, Meta } from '@storybook/addon-docs/blocks';
 import elementsDemo from './demo/elements.twig';
 import stylesDemo from './demo/styles.twig';
-import stylesDarkDemo from './demo/styles-dark.twig';
 
 <Meta
   title="Components/Button"
@@ -35,10 +34,7 @@ Some buttons may not require as much emphasis as others. The `c-button--secondar
 All the above visual styles will appear slightly different within [our dark theme](/?path=/docs/themes--dark). These versions retain their visual emphasis relative to one another while remaining visually distinct from form inputs.
 
 <Canvas>
-  <Story
-    name="Styles (Dark)"
-    parameters={{ themes: { disable: true }, paddings: { disabled: true } }}
-  >
-    {(args) => stylesDarkDemo(args)}
+  <Story name="Styles (Dark)" parameters={{ theme: 't-dark' }}>
+    {(args) => stylesDemo(args)}
   </Story>
 </Canvas>

src/design/demo/theme.twig

@@ -1,29 +1,25 @@
-{% extends '@cloudfour/design/demo/fill-canvas.twig' %}
-
-{% block content %}
-  {% embed '@cloudfour/objects/rhythm/rhythm.twig' with {
-    class: 'o-rhythm--generous'
-  } %}
-    {% block content %}
-      <h1>t-{{theme}}</h1>
-      {% include '@cloudfour/design/typography/demo/inline-elements.twig' only %}
-      {% include '@cloudfour/components/button/demo/styles.twig' only %}
-      {# TODO: Replace padding and corner modifiers once card component can
-         handle these variations natively #}
-      {% set _card_class = 'c-card--horizontal@m u-pad-1 u-rounded' %}
-      {% if theme == 'light' %}
-        {% set _card_class = _card_class ~ ' t-dark' %}
-      {% else %}
-        {% set _card_class = _card_class ~ ' t-light' %}
-      {% endif %}
-      {% include '@cloudfour/components/card/demo/single.twig' with {
-        class: _card_class,
-        href: '#',
-        show_heading: true,
-        show_content: true,
-        show_cover: true,
-        show_footer: true
-      } only %}
-    {% endblock %}
-  {% endembed %}
-{% endblock %}
+{% embed '@cloudfour/objects/rhythm/rhythm.twig' with {
+  class: 'o-rhythm--generous'
+} %}
+  {% block content %}
+    <h1>t-{{theme}}</h1>
+    {% include '@cloudfour/design/typography/demo/inline-elements.twig' only %}
+    {% include '@cloudfour/components/button/demo/styles.twig' only %}
+    {# TODO: Replace padding and corner modifiers once card component can
+        handle these variations natively #}
+    {% set _card_class = 'c-card--horizontal@m u-pad-1 u-rounded' %}
+    {% if theme == 'light' %}
+      {% set _card_class = _card_class ~ ' t-dark' %}
+    {% else %}
+      {% set _card_class = _card_class ~ ' t-light' %}
+    {% endif %}
+    {% include '@cloudfour/components/card/demo/single.twig' with {
+      class: _card_class,
+      href: '#',
+      show_heading: true,
+      show_content: true,
+      show_cover: true,
+      show_footer: true
+    } only %}
+  {% endblock %}
+{% endembed %}

src/design/themes.stories.mdx

@@ -2,17 +2,7 @@ import { Meta, Story, Canvas } from '@storybook/addon-docs/blocks';
 import demo from './demo/theme.twig';
 const demoStory = (args) => demo(args);
 
-<Meta
-  title="Design/Themes"
-  parameters={{ themes: { disable: true }, paddings: { disabled: true } }}
-  argTypes={{
-    theme: {
-      type: { name: 'string' },
-      control: { type: 'inline-radio', options: ['light', 'dark'] },
-      defaultValue: 'light',
-    },
-  }}
-/>
+<Meta title="Design/Themes" />
 
 # Themes
 
@@ -23,15 +13,17 @@ Themes may be applied to a containing element to change that content's appearanc
 The default theme, applied to the document `:root` by default.
 
 <Canvas>
-  <Story name="Light">{demoStory.bind({})}</Story>
+  <Story name="Light" args={{ theme: 'light' }}>
+    {demoStory.bind({})}
+  </Story>
 </Canvas>
 
 ## Dark
 
 Optimized for page intros and headings.
 
 <Canvas>
-  <Story name="Dark" args={{ theme: 'dark' }}>
+  <Story name="Dark" parameters={{ theme: 't-dark' }} args={{ theme: 'dark' }}>
     {demoStory.bind({})}
   </Story>
 </Canvas>