Better bigger/smaller heading icons

src/css/simplemde.css

@@ -132,6 +132,14 @@
 	content: "3";
 }
 
+.editor-toolbar a.fa-header-bigger:after {
+	content: "▲";
+}
+
+.editor-toolbar a.fa-header-smaller:after {
+	content: "▼";
+}
+
 .editor-toolbar.disabled-for-preview a:not(.fa-eye):not(.fa-arrows-alt):not(.fa-columns) {
 	pointer-events: none;
 	background: #fff;

src/js/simplemde.js

@@ -615,13 +615,13 @@ var toolbarBuiltInButtons = {
 	"heading-smaller": {
 		name: "heading-smaller",
 		action: toggleHeadingSmaller,
-		className: "fa fa-header",
+		className: "fa fa-header fa-header-x fa-header-smaller",
 		title: "Smaller Heading (Ctrl+H)",
 	},
 	"heading-bigger": {
 		name: "heading-bigger",
 		action: toggleHeadingBigger,
-		className: "fa fa-lg fa-header",
+		className: "fa fa-header fa-header-x fa-header-bigger",
 		title: "Bigger Heading (Shift+Ctrl+H)",
 	},
 	"heading-1": {