Add super big font size.

rainfall/theme.json

@@ -78,6 +78,11 @@
 					"name": "Extra large",
 					"size": "2rem",
 					"slug": "x-large"
+				},
+				{
+					"name": "Ginormous",
+					"size": "6.5rem",
+					"slug": "xx-large"
 				}
 			]
 		}