Move theme selector to the header and improved about page and styling

src/components/PageSection.js

@@ -0,0 +1,30 @@
+import React from "react";
+import styled, { css } from "styled-components";
+
+export const Content = styled.div`
+  ${({ content }) =>
+    content === PageSection.content.center &&
+    css`
+      max-width: 60rem;
+      margin: 0 auto;
+      // padding: 0.5em;
+    `}
+`;
+
+const contentPosition = {
+  center: "center",
+  stretch: "stretch"
+};
+
+export const PageSection = ({ content, children, className } = { content: contentPosition.stretch }) => {
+  return (
+    <div className={className}>
+      <Content content={content}>{children}</Content>
+    </div>
+  );
+};
+
+PageSection.content = contentPosition;
+PageSection.Content = Content;
+
+export default PageSection;