Feature/syntaxhighlighting (#9)

* wip code highlighting of lines

* Implements gutter component

* WIP: Profiler with gutter

* cleaned up highlight code

* Removes before content for gutter styling

* Styles gutter

* Add correct Profiler code content

* Adds color variable for gutter gray

* refactor code component width gutter and diffing

packages/dev-tools-pages/ts/components/Intro.tsx

@@ -43,6 +43,7 @@ const IntroLead = styled(Lead)`
 `;
 const IntroAside = styled.div`
     max-width: 32.5rem;
+    position: relative; 
 
     ${media.small`
         margin-left: -30px;