[website] [css] changed default button color
diff --git a/website/css/website.css b/website/css/website.css
index df37821..816b3ef 100644
--- a/website/css/website.css
+++ b/website/css/website.css
@@ -134,4 +134,35 @@
 
 .accordion-heading, .accordion-inner {
 	padding-left: 10px;
-}
\ No newline at end of file
+}
+
+/* buttons */
+.btn-default {
+  color: #ffffff;
+  background-color: #a7a9aa;
+  border-color: #a7a9aa;
+}
+
+.btn-default:hover,
+.btn-default:focus,
+.btn-default:active,
+.btn-default.active {
+  background-color: #9a9c9d;
+  border-color: #8d9091;
+}
+
+.btn-default.disabled:hover,
+.btn-default[disabled]:hover,
+fieldset[disabled] .btn-default:hover,
+.btn-default.disabled:focus,
+.btn-default[disabled]:focus,
+fieldset[disabled] .btn-default:focus,
+.btn-default.disabled:active,
+.btn-default[disabled]:active,
+fieldset[disabled] .btn-default:active,
+.btn-default.disabled.active,
+.btn-default[disabled].active,
+fieldset[disabled] .btn-default.active {
+  background-color: #a7a9aa;
+  border-color: #a7a9aa;
+}