Typo3 backend css keeps disappearing?

I have a typo3 system which works mostly fine, however when ever I install a new extension the CSS on the back-end goes away, or seems to be parsed only partially.

screen shot at : http://i.imgur.com/gF8Fa.png

I've tried several different extension and they a开发者_JAVA技巧ll seem to do this.

Typo3 version 4.4.6

If anyone has any ideas... all help is valued and appreciated. Ta!

Please make sure that you have installed the system extension "t3skin". It brings the default skin and is shipped with TYPO3.

If it is installed, check whether your .htaccess has the gzip rules enabled, in case of you have $TYPO3_CONF_VARS['BE']['compressionLevel'] set.

I guess you have some trouble with gzip compressed css here. Newer versions of TYPO3 added this feature to speed things up. Typically TYPO3 can't write to your .htaccess file which is why you have to do it manually. Just add the following lines to your .htaccess file:

 <FilesMatch "\.js\.gzip$">
 AddType "text/javascript" .gzip
 </FilesMatch>
 <FilesMatch "\.css\.gzip$">
  AddType "text/css" .gzip
  </FilesMatch>
  AddEncoding gzip .gzip

Note that the .htaccess file is hidden and some ftp / sftp clients won't find it with their default settings. That's basically what StephenKing says just a lil more elaborate.

Try this in localconf.php:

$TYPO3_CONF_VARS['BE']['compressionLevel'] = '0'

It helped in my installation.

In my case I had mod_deflate installed and good .htaccess, but in vhost configuration .htaccess reading was disabled by AllowOverride None, so I turned AllowOverride in All and all worked.

AllowOverride All

Restart Apache :

apache2ctl restart