[TYPO3-english] How to change the width of the module container in backend

[Patrick Rodacker]

Hi list,

what's the best way to set the width of the module container 
(id=typo3-side-menu) in the backend?

AFAIK there is not way to set this using a TSConfig setting or 
configuration setting of TYPO3_CONF_VARS, so I wonder how it would be 
possible to set the width of container?

Could I include a custom css file overriding the default settings or 
should there be a skin extension created integrating the new css values?

Any help appreciated

Patrick