GoShawk.cc por hemme

To remove shadows:
1) Go to about:config and enable: toolkit.legacyUserProfileCustomizations.stylesheets
2) Go to about:support and open your Profile folder
3) Create \chrome\userChrome.css:

.tabbrowser-tab .tab-label {
text-shadow: none !important;
}
#PersonalToolbar .bookmark-item {
text-shadow: none !important;
}
#nav-bar .toolbarbutton-text,
#toolbar-menubar .toolbarbutton-text {
text-shadow: none !important;
}