Custom CSS in TYPO3 backend

To be able to adjust some non-configurable menu items I wanted to inject my own CSS into the TYPO3 backend. ​

TYPO3 combines all CSS and JavaScript files in the backend automatically, so in order to be able to debug your custom CSS you have to turn that off at first: ​

$TYPO3_CONF_VARS['BE']['debug'] = 1;

Now that CSS files do not get merged anymore, you can load your CSS in the additional configuration file or you extension's ext_tables.php: ​

$GLOBALS['TBE_STYLES']['stylesheet'] = '/path/to/style.css'