diff --git a/src/index.js b/src/index.js
index ada83d8..f3e1d19 100644
--- a/src/index.js
+++ b/src/index.js
@@ -125,6 +125,11 @@ export default function applyConfig(config) {
     { cssClass: 'red-text', label: 'Red text' },
     { cssClass: 'yellow-text', label: 'Yellow text' },
     { cssClass: 'grey-text', label: 'Grey text' },
+
+    // font-sizes
+    { cssClass: 'x-large', label: 'x-large' },
+    { cssClass: 'xx-large', label: 'xx-large' },
+    { cssClass: 'xxx-large', label: 'xxx-large' },
   ];
   // config.settings.slate.styleMenu.blockStyles = [
   //   ...config.settings.slate.styleMenu.blockStyles,
diff --git a/src/slate-styles.css b/src/slate-styles.css
index ba649dd..9124e3a 100644
--- a/src/slate-styles.css
+++ b/src/slate-styles.css
@@ -157,3 +157,17 @@
 .black-gainsboro-text {
   color: #e3e3e3;
 }
+
+/* font sizes */
+
+.x-large {
+  font-size: x-large;
+}
+
+.xx-large {
+  font-size: xx-large;
+}
+
+.xxx-large {
+  font-size: xxx-large;
+}