feat(storybooy): add styles to body

This commit adds general theme styles to storybook so that aligns with
the application theme.

Author: maybeast

.storybook/preview-body.html

@@ -0,0 +1,12 @@
+<style>
+  body {
+    color: #fff;
+    margin: 0;
+    font-size: 0.875rem;
+    font-family: "Roboto", "Helvetica", "Arial", sans-serif;
+    font-weight: 400;
+    line-height: 1.43;
+    letter-spacing: 0.01071em;
+    background-color: #303030;
+  }
+</style>