Updated dev dependencies

build/css/simple-keyboard.css

@@ -1,6 +1,6 @@
 /*!
  * 
- *   simple-keyboard v2.15.4 (Non-minified build)
+ *   simple-keyboard v2.15.5 (Non-minified build)
  *   https://github.com/hodgef/simple-keyboard
  * 
  *   Copyright (c) Francisco Hodge (https://github.com/hodgef)
@@ -29,6 +29,7 @@ html {
 }
 
 .simple-keyboard .hg-row {
+  display: -webkit-flex;
   display: flex;
 }
 
@@ -42,7 +43,8 @@ html {
 
 .simple-keyboard .hg-button {
   display: inline-block;
-  flex-grow: 1;
+  -webkit-flex-grow: 1;
+          flex-grow: 1;
   cursor: pointer;
 }
 
@@ -64,9 +66,12 @@ html {
   background: white;
   border-bottom: 1px solid #b5b5b5;
   cursor: pointer;
+  display: -webkit-flex;
   display: flex;
-  align-items: center;
-  justify-content: center;
+  -webkit-align-items: center;
+          align-items: center;
+  -webkit-justify-content: center;
+          justify-content: center;
 }
 
 /* When using option "useButtonTag" */
@@ -83,9 +88,12 @@ html {
 .simple-keyboard.hg-theme-default.hg-layout-numeric .hg-button {
   width: 33.3%;
   height: 60px;
-  align-items: center;
+  -webkit-align-items: center;
+          align-items: center;
+  display: -webkit-flex;
   display: flex;
-  justify-content: center;
+  -webkit-justify-content: center;
+          justify-content: center;
 }
 
 .simple-keyboard.hg-theme-default .hg-button.hg-button-numpadadd {