Enter this in SETUP:
plugin.tx_cssstyledcontent._CSS_DEFAULT_STYLE >
Doing this will clear all that extra CSS you get, but will also have some negative effects.
quote from http://bugs.typo3.org/view.php?id=1636:
The css styles from the integrated cron_cssstyledcontent are vital for positioning of the elements, so this cannot be a “reference” implementation: without it, no image positioning would work, many users would be frustrated. A second reason to have this in TypoScript is that it makes use of some constants that can be set through the constant editor (border color, margins, etc), so that the generated css includes this information dynamically. These constants also are well known and provide a “smoother” transition from table-based styles to the css-styled-approach, without having to adapt any css-styles on your site.