Fix hero buttons to be clickable (#373)

src/pages/index.js

@@ -116,6 +116,11 @@ class Home extends Component {
                 },
               },
             }}>
+            <div
+              css={{
+                // Content should be above absolutely-positioned hero image
+                position: 'relative',
+              }}>
               <Container>
                 <h1
                   css={{
@@ -177,6 +182,7 @@ class Home extends Component {
                 </Flex>
               </Container>
             </div>
+          </div>
         </header>
 
         <Container>