I started using openSUSE only recently. openSUSE needed some work in the beginning as I was new on the OS, but more I used it more I liked it. The only eyesore on openSUSE, with Gnome 3 was font rendering in Firefox. I tried couple of methods but none worked. Then I found the solution and I am sharing with you so that if you are one of such users like me you can get benefit from it. The credit goes to the developer who created the fix -- Muzlocker.
First you need to add a repository. Open Install/Remove Software aka Software Manager and from Configuration menu, open repositories.
Now, click on 'Add' button and select 'specify URL' and next. Here add this line in the URL section:
You can put any name in the 'Repository Name' section, but do put a name so that you can recognizer it. I entered Muzlocker. Click next and follow instructions. Once the repo is added from Groups select repositories, there you will see Muzlocker. Click on Muzlocker and select these packages:
Click apply and install.
Now go to Advance Settings and from Fonts select Droid Sans. Hinting will be none and Antiliasing will be Rgba. Reboot your system and your system and Firefox fonts will be perfect.
This is how my Firefox page looks now: