refactor: add reusable styles properties

src/components/Author/styles.ts

@@ -1,10 +1,11 @@
 import styled from 'react-emotion';
 import ListItem from '@material-ui/core/ListItem';
 import Typography from '@material-ui/core/Typography';
+import { fontWeight } from '../../utils/styles/sizes';
 
 export const Heading = styled(Typography)({
   '&&': {
-    fontWeight: 700,
+    fontWeight: fontWeight.bold,
     textTransform: 'capitalize',
   },
 });