Firefox got ugly after update to 11.3

I updated to 11.3 and my Firefox became ugly. It now looks like this:
http://i54.tinypic.com/8yb5lv.jpg

It used to look something like this with 11.2:
http://i53.tinypic.com/2myynn4.jpg

Firefox still uses KDE file dialogs etc. so at least some of the Kde integration still works. How can make firefox look like it belongs to Kde desktop. I already tried reinstalling firefox and also removing .mozilla folder.

Thank you.

I resolved it going to System Settings>Style>GTK Styles and choosing QTCurve

Thank you! It worked. I had to install qtcurve first as it wasn’t installed by default for some reason.