Fix z-index problem in LeftSidebarWithMenu

This applies the z-index fix which causes the sidebar menu to
overlap with sidebar main.

package.json

@@ -1,5 +1,5 @@
 {
-	"version": "0.2.3",
+	"version": "0.2.4",
 	"license": "MIT",
 	"main": "dist/index.js",
 	"typings": "dist/index.d.ts",

src/layouts/LeftSidebarWithMenu/index.tsx

@@ -50,6 +50,7 @@ const SidebarMain = styled('div')({
 	height: '100%',
 	paddingTop: 'inherit',
 	paddingBottom: 'var(--size-menu, 4rem)',
+	zIndex: 2,
 	[minWidthFactor(3)]: {
 		position: 'absolute',
 		right: 0,