Fix broken css

src/components/Button.tsx

@@ -9,7 +9,7 @@ const Button = styled.div`
   color: inherit;
   text-decoration: none;
 
-  :hover {
+  &:hover {
     background: ${props => props.theme.highlight};
   }
 

src/components/MenuButton.tsx

@@ -92,7 +92,7 @@ const Menu = styled.ul`
   }
 
   > li.selected {
-    ::before {
+    &::before {
       content: '*';
       font-weight: bold;
     }