increase color transition time in buttons

res/css/components/button.less

@@ -10,7 +10,7 @@
     z-index: 2;
     overflow: hidden;
     cursor: pointer;
-    transition: color .1s, background-color .2s, transform .2s;
+    transition: color .2s, background-color .2s, transform .2s;
     vertical-align: middle;
     font-weight: 500;
     margin: 0;