Upgrade to Sass

This way its much easier to edit and personalize each theme.

assets/css/main.scss

@@ -0,0 +1,8 @@
+---
+
+---
+
+@charset "utf-8";
+
+@import "skins/{{ site.theme_skin | default: 'blue' }}"; // skin
+@import "default"; // main partials