https://imgur.com/a/UnrKI That is the window I see when launching audio volume settings from the applet. Launching audio volume settings from kcm results in normal styling. Steps to reproduce: 1) Right click applet 2) Launch Audio Volume Settings and Click on Audio Volume Tab Systems: Laptop and Desktop on Kubuntu 17.10 w/ Kubuntu Backports (plasma 5.12, kde frameworks 5.42, qt 5.9.1)
*** This bug has been marked as a duplicate of bug 388766 ***