theming the add package button

theme/style.less

@@ -87,6 +87,14 @@
     padding:7px;
 }
 
+#blocklyAddPackage {
+    text-align: left;
+}
+#blocklyAddPackage button {
+    background-color: rgba(0, 0, 0, 0.3);
+    color: white;
+}
+
 .organization {
     top: 1.6em;
 }