Fix last menu item is cut on Firefox

Author: fzaninotto

examples/demo/src/layout/Menu.tsx

@@ -155,6 +155,7 @@ const Menu = ({ dense = false }: MenuProps) => {
 const useStyles = makeStyles(theme => ({
     root: {
         marginTop: theme.spacing(1),
+        marginBottom: theme.spacing(1),
         transition: theme.transitions.create('width', {
             easing: theme.transitions.easing.sharp,
             duration: theme.transitions.duration.leavingScreen,

packages/ra-ui-materialui/src/layout/Menu.tsx

@@ -22,6 +22,7 @@ const useStyles = makeStyles(
             flexDirection: 'column',
             justifyContent: 'flex-start',
             marginTop: '0.5em',
+            marginBottom: '1em',
             [theme.breakpoints.only('xs')]: {
                 marginTop: 0,
             },