How to change firefox default tab size and fix wonky tab behavior

Under your profile folder create a chrome/ folder

cd /home/`whoami`/.mozilla/firefox/*default*
mkdir chrome
cd chrome

Create userChrome.css file

touch userChrome.css

Update userChrome.css with the following lines:

@namespace url(;
.tabbrowser-tab:not([pinned]) {
max-width: 80px !important;
.tabbrowser-tab:not([pinned]):not([fadein]) {
max-width: 0.1px !important;


Restart firefox and enjoy

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How to downgrade to Firefox 56.0

Backup your current settings if needed

cp -rp .mozilla/ .mozilla_bk

Purge current firefox

sudo apt-get purge firefox -y

Download 56 version


sudo su

tar -xvf firefox-56.0.tar.bz2

cp -rp firefox /opt/

cd /usr/bin

ln -s /opt/firefox/firefox firefox

Finally, you have to avoid upgrading to the newer version.… Read the rest