I encounter a problem for changing font color in firefox toolbar. I tried change via firefox’s preferences->content->font->color but it failed. Sometimes, a themes will make it hard to view it. Well what has happened is the system font color is the same color as your firefox theme color.
So to correct this is very simple. All you need is to create the userChrome.css file. That simple! But, where i can create the file? Follow the instructions below:
#Open your Home Folder. In the toolbar click view and then show hidden files. Oopen .mozilla>firefox>(the default folder)>chrome
#Here you create the file name userChrome.css and add this code to the page:
menubar, menubutton, menu, menuitem, menupopup, popup > * {
color: white !important;
}
#Save this file as userChrome.css in the chrome folder
Now all you need to do is restart or close and open Firefox, your font will be white.

