implement bubble view

src/resources/style.css

@@ -13,4 +13,8 @@
     /* Invert the y-axis, so the messages are drawn bottom-to-top */
     /* Individual messages are drawn upside down in the custom renderer */
     transform: scale(1, -1);
+}
+
+.message-drawing-area {
+    color: darker(@accent_bg_color);
 }