GTK program If nothing changes in the KDE4 below will be "nude", kubuntu default installed Gtk2-engines-qtcurve (see System Settings-automatic startup). If you want to GTK the program to use the Gnome theme under KDE4, you can do so.
sudo apt install gtk-theme-switch
Then run GTK-THEME-SWITCH2, select the theme
The human of the yellow soil
You can http://www.aliyun.com/zixun/aggregation/8601.html in Kpackagekit "> search keyword human install ubuntu default earthy yellow gnome theme. System settings-appearance-color-options, removing "apply colors to non-KDE4 applications"
If you want to solve better, then
sudo apt install Firefox
If already installed, remove and then install, note: Must not
sudo apt autoremove
Otherwise just installed style bag is completely unloaded, you most remove the new stand, get more you will find no meaning, how to get all is flawed ... Finally, the habit of Simply naked Firefox
Clearlook
System settings-appearance-color-options, tick "apply color to non KDE4 application" and GTK theme selection Clearlook
Effect chart