implement CssJail

.storybook/config.js

-import { configure } from '@storybook/react';
+import React from 'react';
+import { configure, addDecorator } from '@storybook/react';
 import { setOptions } from '@storybook/addon-options';
 
+import CssJail from '../src/CssJail';
+
 setOptions({
   name: '💎 PARAGON',
   url: 'https://github.com/edx/paragon',
@@ -9,6 +12,12 @@ setOptions({
 
 const req = require.context('../src', true, /\.stories\.jsx$/);
 
+addDecorator(story => (
+  <CssJail>
+    {story()}
+  </CssJail>
+));
+
 function loadStories() {
   require('./Paragon.stories.jsx');
   req.keys().forEach((filename) => req(filename));

src/CssJail/CssJail.scss

+.css-jail {
+    @import "~bootstrap/scss/_reboot";
+
+    -ms-text-size-adjust: 100%;
+    -webkit-text-size-adjust: 100%;
+    box-sizing: border-box;
+    line-height: 1.15;
+
+    font-size: $font-size-base;
+    font-weight: $font-weight-base;
+    line-height: $line-height-base;
+    margin: 0;
+    color: $body-color;
+    background-color: $body-bg;
+}

src/CssJail/index.jsx

+import React from 'react';
+import PropTypes from 'prop-types';
+
+import styles from './CssJail.scss';
+
+function CssJail({ children }) {
+  return (
+    <div
+      style={{ fontFamily: 'sans-serif' }}
+      className={styles['css-jail']}
+    >
+      {children}
+    </div>
+  );
+}
+
+CssJail.propTypes = {
+  children: PropTypes.element.isRequired,
+};
+
+export default CssJail;