revert position to static and make that fix in a separate PR since it has nothing to do with upgrading react-modal

Author: David

components/modal/index.jsx

@@ -426,7 +426,7 @@ class Modal extends React.Component {
 				padding: 'default',
 			},
 			overlay: {
-				position: 'absolute',
+				position: 'static',
 				backgroundColor: 'default',
 			},
 		};