It’s surprisingly easy: create a textpattern.css file with only the rules you need to change (like the lines above). Create a theme manifest that refers back to the classic theme— something like this†:

<?php

if (!defined(‘txpinterface’)) die(‘txpinterface is undefined.’);

theme::based_on(‘classic’);

class MyCustom_theme extends classic_theme
{

function manifest() { return array( ‘title’ => ‘MyCustom’, ‘author’ => ‘J.K. Rowling’, ‘author_uri’ => ‘http://google.com/’, ‘version’ => ’0.1’, ‘description’ => ‘Posuere exer uptatem alisis incinim suscil vulput fringilla.’, ‘help’ => ‘’, ); }
}
?>

Save both files in a directory called MyCustom (or whatever you name the theme) under themes, and you’re ready to roll. Then, just activate the theme under Advanced Prefs.

† The comment input here strips out line breaks and tabs, but you can see plenty of example manifests at Textgarden for the canonical formating.

John, thanks for the excellent writeup. This tip has been published “as-is” and I was hopeful that others would chip in with some further options.

May I ask that you write a tutorial on creating an admin theme based on your comment above? I think that would be very helpful and we have not yet touched much on the new 4.2 features.