added compass, added some basic stylesheets

source/stylesheets/library/_opacity.sass

@@ -0,0 +1,18 @@
+//**
+  Provides cross-browser css opacity.
+  @param !opacity
+    A number between 0 and 1, where 0 is transparent and 1 is opaque.
+=opacity(!opacity)
+  :opacity= !opacity
+  :-moz-opacity= !opacity
+  :-khtml-opacity= !opacity
+  :-ms-filter= "progid:DXImageTransform.Microsoft.Alpha(Opacity=" + round(!opacity*100) + ")"
+  :filter= "alpha(opacity=" + round(!opacity*100) + ")"
+
+// Make an element completely transparent.
+=transparent
+  +opacity(0)
+
+// Make an element completely opaque.
+=opaque
+  +opacity(1)