After creating a new theme for my Silverstripe powered site, I noticed that the text and hyperlink colours in the CMS administration panel were all skewed.
After poking around, I recognised that CMS was pulling the typography.css file from my theme. Subsequently, this resulted in abnormally large text and unexpected colours while browsing the administration interface.
I'm interested to hear the justification for doing this. I was under the impression that published site and administration panel were entirely different.
At any rate, you can prevent this happening by commenting out line 68 in cms/CMSMain.php with SS 2.1.