This screencast is a part of the epic learning series "Four weeks of Drupal", chapter "Introduction to theming". You can view the full series at dev.nodeone.se/en/four-weeks-of-drupal.
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This screencast shows an alternative – and better – way of overriding small parts of CSS. Instead of overriding the entire CSS file, you can simply add your own file with selective overrides. Pretty smart, when you think about it (since you can continue to rely on the original styling for all the things you *don't* override).