Green links
The general color of hattrick is green and so are all links on the site. When HT's also made all denomination links clickable it became a bit dazzling to the eyes according to some managers. By downloading a modified stylesheet made by pnothy you could make the green denomination links black again, while all other links will stay green.
Place the file in the chrome folder for your FireFox profile. It is usually located at the following location: C:\Documents and Settings\your username\Application Data\Mozilla\Firefox\Profiles\something with default in it\chrome. In case you are not able to find this folder, try searching with the Windows find function for the word 'chrome'. The Application Data folder may be hidden, so you might have to check 'show hidden files and maps' in map-options.
Restart firefox and you're done. Optionally you can choose another desired color by editing the stylesheet yourself.