Update README

README.adoc

@@ -36,6 +36,14 @@ To install the application, you can do:
 
  # meson install
 
+Configuration
+-------------
+The standard means to adjust the looks of the program is through GTK+ 3 CSS.
+As an example, to tightly pack browser items, put the following in your
+_~/.config/gtk-3.0/gtk.css_:
+
+ fastiv-browser { -FastivBrowser-spacing: 0; padding: 0; border: 0; margin: 0; }
+
 Contributing and Support
 ------------------------
 Use https://git.janouch.name/p/fastiv to report any bugs, request features,