Site content and style update for sprint2/3 (#279)

* add legend and styling for map page
* update header to latest style/content
* add contact page
* add methodology page
#199 and #200

client/src/pages/methodology.tsx

@@ -0,0 +1,46 @@
+import * as React from 'react';
+import Layout from '../components/layout';
+
+interface MethodPageProps {
+  location: Location;
+}
+
+// markup
+const IndexPage = ({location}: MethodPageProps) => {
+  return (<Layout location={location}>
+    <section className={'usa-prose'}>
+      <h1>Methodology</h1>
+      <p>
+        The Just Progress tool combines demographic, environmental, and
+        socio-economic data to generate a cumulative index score, referred to
+        as the Just Progress Index. The tool currently utilizes national,
+        publically-available data from the United States Census Bureau’s
+        American Community Survey (ACS) and the EPA’s EJScreen tool.
+      </p>
+      <p>
+        The various inputs into the Just Progress Index are averaged into 2
+        categories: Pollution Burden and Demographics.
+      </p>
+      <p>
+        Pollution Burden: health risks arising from proximity and potential
+        exposures to pollution and other adverse environmental conditions
+      </p>
+      <p>
+        Demographics: sensitive populations and socioeconomic factors that
+        make a community more vulnerable
+      </p>
+      <p>
+        <b>Pollution Burden average x Demographics average = Just Progress
+          Index</b>
+      </p>
+
+      <h2>Just Progress Index datasets</h2>
+
+      <p><i>Data pending</i></p>
+
+    </section>
+  </Layout>
+  );
+};
+
+export default IndexPage;