keep first/last buttons within userform-progress div

javascript/UserForm.js

@@ -431,6 +431,14 @@ jQuery(function ($) {
 				buttonOffset = -1 * ($button.innerWidth() / 2);
 
 			$button.css({left: leftPercent, marginLeft: buttonOffset});
+
+			// First and last buttons are kept within userform-progress container
+			if (index === self.$jsAlign.length - 1) {
+				$button.css({marginLeft: buttonOffset * 2});
+			} else if (index === 0) {
+				$button.css({marginLeft: 0});
+			}
+
 		});
 
 		this.update(1);